diff --git a/src/pocketmine/Player.php b/src/pocketmine/Player.php
index 4fbe939c0..e047edd0e 100644
--- a/src/pocketmine/Player.php
+++ b/src/pocketmine/Player.php
@@ -193,7 +193,6 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 	protected $chunksPerTick;
 	/** @var null|Position */
 	private $spawnPosition = null;
-	private $inAction = false;
 
 	protected $inAirTicks = 0;
 	protected $lastSpeedTick = 0;
@@ -251,10 +250,6 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 		return $this->namedtag instanceof Compound;
 	}
 
-	protected function initEntity(){
-		parent::initEntity();
-	}
-
 	/**
 	 * @param Player $player
 	 */
@@ -669,6 +664,8 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 			$this->teleport($ev->getRespawnPosition());
 
 			$this->sendSettings();
+			$this->sendData($this);
+			$this->sendPotionEffects($this);
 			$this->inventory->sendContents($this);
 			$this->inventory->sendArmorContents($this);
 
@@ -829,8 +826,8 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 		$this->sleeping = clone $pos;
 		$this->teleport(new Position($pos->x + 0.5, $pos->y + 1, $pos->z + 0.5, $this->level));
 
-		$this->sendMetadata($this->getViewers());
-		$this->sendMetadata($this);
+		$this->setDataProperty(self::DATA_PLAYER_BED_POSITION, self::DATA_TYPE_POS, [$pos->x, $pos->y, $pos->z]);
+		$this->setDataFlag(self::DATA_PLAYER_FLAGS, self::DATA_PLAYER_FLAG_SLEEP, true);
 
 		$this->setSpawn($pos);
 		$this->tasks[] = $this->server->getScheduler()->scheduleDelayedTask(new CallbackTask([$this, "checkSleep"]), 60);
@@ -863,9 +860,8 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 			$this->server->getPluginManager()->callEvent($ev = new PlayerBedLeaveEvent($this, $this->level->getBlock($this->sleeping)));
 
 			$this->sleeping = null;
-
-			$this->sendMetadata($this->getViewers());
-			$this->sendMetadata($this);
+			$this->setDataFlag(self::DATA_PLAYER_FLAGS, self::DATA_PLAYER_FLAG_SLEEP, false);
+			$this->setDataProperty(self::DATA_PLAYER_BED_POSITION, self::DATA_TYPE_POS, [0, 0, 0]);
 		}
 
 	}
@@ -1680,10 +1676,7 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 
 				$this->inventory->sendHeldItem($this->hasSpawned);
 
-				if($this->inAction === true){
-					$this->inAction = false;
-					$this->sendMetadata($this->getViewers());
-				}
+				$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_ACTION, false);
 				break;
 			case ProtocolInfo::USE_ITEM_PACKET:
 				if($this->spawned === false or $this->dead === true or $this->blocked){
@@ -1697,10 +1690,7 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 				$packet->eid = $this->id;
 
 				if($packet->face >= 0 and $packet->face <= 5){ //Use Block, place
-					if($this->inAction === true){
-						$this->inAction = false;
-						$this->sendMetadata($this->getViewers());
-					}
+					$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_ACTION, false);
 
 					if($blockVector->distance($this) > 10){
 
@@ -1797,9 +1787,8 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 							$snowball->spawnToAll();
 						}
 					}
-					$this->inAction = true;
+					$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_ACTION, true);
 					$this->startAction = microtime(true);
-					$this->sendMetadata($this->getViewers());
 				}
 				break;
 			case ProtocolInfo::PLAYER_ACTION_PACKET:
@@ -1875,8 +1864,7 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 						}
 
 						$this->startAction = false;
-						$this->inAction = false;
-						$this->sendMetadata($this->getViewers());
+						$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_ACTION, false);
 						break;
 					case 6: //get out of the bed
 						$this->stopSleep();
@@ -2080,15 +2068,14 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 				$this->teleport($ev->getRespawnPosition());
 
 				$this->fireTicks = 0;
-				$this->airTicks = 300;
+				$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, 300);
 				$this->deadTicks = 0;
 				$this->noDamageTicks = 60;
 
 				$this->setHealth(20);
 				$this->dead = false;
 
-				$this->sendMetadata($this->getViewers());
-				$this->sendMetadata($this);
+				$this->sendData($this);
 
 				$this->sendSettings();
 				$this->inventory->sendContents($this);
@@ -2107,10 +2094,8 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 				}
 				$this->craftingType = 0;
 
-				if($this->inAction === true){
-					$this->inAction = false;
-					$this->sendMetadata($this->getViewers());
-				}
+				$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_ACTION, false); //TODO: check if this should be true
+
 				switch($packet->event){
 					case 9: //Eating
 						$items = [
@@ -2182,10 +2167,7 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 
 				$this->level->dropItem($this->add(0, 1.3, 0), $item, $motion, 40);
 
-				if($this->inAction === true){
-					$this->inAction = false;
-					$this->sendMetadata($this->getViewers());
-				}
+				$this->setDataFlag(self::DATA_FLAGS, self::DATA_FLAG_ACTION, false);
 				break;
 			case ProtocolInfo::MESSAGE_PACKET:
 				if($this->spawned === false or $this->dead === true){
@@ -2701,30 +2683,6 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 		}
 	}
 
-	public function getData(){ //TODO
-		$flags = 0;
-		$flags |= $this->fireTicks > 0 ? 1 : 0;
-		$flags |= $this->hasEffect(Effect::INVISIBILITY) ? 1 << 5 : 0;
-		//$flags |= ($this->crouched === true ? 0b10:0) << 1;
-		$flags |= ($this->inAction === true ? 0b10000 : 0);
-		$d = [
-			0 => ["type" => 0, "value" => $flags],
-			1 => ["type" => 1, "value" => $this->airTicks],
-			3 => ["type" => 0, "value" => $this->hasEffect(Effect::INVISIBILITY) ? 0 : 1],
-			16 => ["type" => 0, "value" => 0],
-			17 => ["type" => 6, "value" => [0, 0, 0]],
-		];
-
-
-		if($this->sleeping instanceof Vector3){
-			$d[16]["value"] = 2;
-			$d[17]["value"] = [$this->sleeping->x, $this->sleeping->y, $this->sleeping->z];
-		}
-
-
-		return $d;
-	}
-
 	public function teleport(Vector3 $pos, $yaw = null, $pitch = null){
 		if(parent::teleport($pos, $yaw, $pitch)){
 
@@ -2735,7 +2693,7 @@ class Player extends Human implements CommandSender, InventoryHolder, IPlayer{
 				$this->removeWindow($window);
 			}
 
-			$this->airTicks = 300;
+			$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, 300);
 			$this->resetFallDistance();
 			$this->orderChunks();
 			$this->nextChunkOrderRun = 0;
diff --git a/src/pocketmine/entity/Effect.php b/src/pocketmine/entity/Effect.php
index 1c78b553a..bea73b385 100644
--- a/src/pocketmine/entity/Effect.php
+++ b/src/pocketmine/entity/Effect.php
@@ -23,6 +23,9 @@ namespace pocketmine\entity;
 
 use pocketmine\event\entity\EntityDamageEvent;
 use pocketmine\event\entity\EntityRegainHealthEvent;
+use pocketmine\network\protocol\MobEffectPacket;
+use pocketmine\Player;
+use pocketmine\Server;
 
 class Effect{
 	const SPEED = 1;
@@ -136,12 +139,20 @@ class Effect{
 		return $this;
 	}
 
+	/**
+	 * @return int
+	 */
 	public function getAmplifier(){
 		return $this->amplifier;
 	}
 
+	/**
+	 * @param int $amplifier
+	 *
+	 * @return $this
+	 */
 	public function setAmplifier($amplifier){
-		$this->amplifier = $amplifier;
+		$this->amplifier = (int) $amplifier;
 		return $this;
 	}
 
@@ -188,4 +199,44 @@ class Effect{
 				break;
 		}
 	}
+
+	public function add(Entity $entity, $modify = false){
+		$pk = new MobEffectPacket();
+		$pk->eid = $entity->getId();
+		$pk->effectId = $this->getId();
+		$pk->amplifier = $this->getAmplifier();
+		$pk->particles = $this->isVisible();
+		$pk->duration = $this->getDuration();
+		if($modify){
+			$pk->eventId = MobEffectPacket::EVENT_MODIFY;
+		}else{
+			$pk->eventId = MobEffectPacket::EVENT_ADD;
+		}
+
+		Server::broadcastPacket($entity->getViewers(), $pk);
+		if($entity instanceof Player){
+			$entity->dataPacket($pk);
+		}
+
+		if($this->id === Effect::INVISIBILITY){
+			$entity->setDataFlag(Entity::DATA_FLAGS, Entity::DATA_FLAG_INVISIBLE, true);
+			$entity->setDataProperty(Entity::DATA_SHOW_NAMETAG, Entity::DATA_TYPE_BYTE, 0);
+		}
+	}
+
+	public function remove(Entity $entity){
+		$pk = new MobEffectPacket();
+		$pk->eid = $entity->getId();
+		$pk->eventId = MobEffectPacket::EVENT_REMOVE;
+		$pk->effectId = $this->getId();
+		Server::broadcastPacket($entity->getViewers(), $pk);
+		if($entity instanceof Player){
+			$entity->dataPacket($pk);
+		}
+
+		if($this->id === Effect::INVISIBILITY){
+			$entity->setDataFlag(Entity::DATA_FLAGS, Entity::DATA_FLAG_INVISIBLE, false);
+			$entity->setDataProperty(Entity::DATA_SHOW_NAMETAG, Entity::DATA_TYPE_BYTE, 1);
+		}
+	}
 }
diff --git a/src/pocketmine/entity/Entity.php b/src/pocketmine/entity/Entity.php
index f72339885..124ba5531 100644
--- a/src/pocketmine/entity/Entity.php
+++ b/src/pocketmine/entity/Entity.php
@@ -48,6 +48,7 @@ use pocketmine\nbt\tag\Compound;
 use pocketmine\nbt\tag\Double;
 use pocketmine\nbt\tag\Enum;
 use pocketmine\nbt\tag\Float;
+use pocketmine\nbt\tag\Int;
 use pocketmine\nbt\tag\Short;
 use pocketmine\nbt\tag\String;
 use pocketmine\Network;
@@ -66,6 +67,26 @@ abstract class Entity extends Location implements Metadatable{
 
 	const NETWORK_ID = -1;
 
+
+	const DATA_TYPE_BYTE = 0;
+	const DATA_TYPE_SHORT = 1;
+	const DATA_TYPE_INT = 2;
+	const DATA_TYPE_FLOAT = 3;
+	const DATA_TYPE_STRING = 4;
+	const DATA_TYPE_SLOT = 5;
+	const DATA_TYPE_POS = 6;
+	const DATA_TYPE_ROTATION = 7;
+
+	const DATA_FLAGS = 0;
+	const DATA_AIR = 1;
+	const DATA_SHOW_NAMETAG = 3;
+
+
+	const DATA_FLAG_ONFIRE = 0;
+	const DATA_FLAG_ACTION = 4;
+	const DATA_FLAG_INVISIBLE = 5;
+
+
 	public static $entityCount = 1;
 	/** @var Entity[] */
 	private static $knownEntities = [];
@@ -81,6 +102,13 @@ abstract class Entity extends Location implements Metadatable{
 
 	protected $id;
 
+	protected $dataFlags = 0;
+	protected $dataProperties = [
+		self::DATA_FLAGS => [self::DATA_TYPE_BYTE, 0],
+		self::DATA_SHOW_NAMETAG => [self::DATA_TYPE_BYTE, 1],
+		self::DATA_AIR => [self::DATA_TYPE_SHORT, 300]
+	];
+
 	public $passenger = null;
 	public $vehicle = null;
 
@@ -138,7 +166,6 @@ abstract class Entity extends Location implements Metadatable{
 	public $lastUpdate;
 	public $maxFireTicks;
 	public $fireTicks;
-	public $airTicks;
 	public $namedtag;
 	public $canCollide = true;
 
@@ -210,7 +237,7 @@ abstract class Entity extends Location implements Metadatable{
 		if(!isset($this->namedtag->Air)){
 			$this->namedtag->Air = new Short("Air", 300);
 		}
-		$this->airTicks = $this->namedtag["Air"];
+		$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, $this->namedtag["Air"]);
 
 		if(!isset($this->namedtag->OnGround)){
 			$this->namedtag->OnGround = new Byte("OnGround", 0);
@@ -239,23 +266,17 @@ abstract class Entity extends Location implements Metadatable{
 		return $this->effects;
 	}
 
+	public function removeAllEffects(){
+		foreach($this->effects as $effect){
+			$this->removeEffect($effect->getId());
+		}
+	}
+
 	public function removeEffect($effectId){
 		if(isset($this->effects[$effectId])){
-			$pk = new MobEffectPacket();
-			$pk->eid = $this->getId();
-			$pk->eventId = MobEffectPacket::EVENT_REMOVE;
-			$pk->effectId = $effectId;
-			Server::broadcastPacket($this->getViewers(), $pk);
-			if($this instanceof Player){
-				$this->dataPacket($pk);
-			}
-
+			$effect = $this->effects[$effectId];
 			unset($this->effects[$effectId]);
-			
-			$this->sendMetadata($this->hasSpawned);
-			if($this instanceof Player){
-				$this->sendMetadata($this);
-			}
+			$effect->remove($this);
 		}
 	}
 
@@ -264,29 +285,21 @@ abstract class Entity extends Location implements Metadatable{
 	}
 
 	public function addEffect(Effect $effect){
-		$pk = new MobEffectPacket();
-		$pk->eid = $this->getId();
-		$pk->effectId = $effect->getId();
-		$pk->amplifier = $effect->getAmplifier();
-		$pk->particles = $effect->isVisible();
-		$pk->duration = $effect->getDuration();
 		if(isset($this->effects[$effect->getId()])){
-			$pk->eventId = MobEffectPacket::EVENT_MODIFY;
+			$oldEffect = $this->effects[$effect->getId()];
+			if(
+				$effect->getAmplifier() <= $oldEffect->getAmplifier()
+				or ($effect->getAmplifier() === $oldEffect->getAmplifier()
+					and $effect->getDuration() < $oldEffect->getDuration())
+			){
+				return;
+			}
+			$effect->add($this, true);
 		}else{
-			$pk->eventId = MobEffectPacket::EVENT_ADD;
-		}
-
-		Server::broadcastPacket($this->getViewers(), $pk);
-		if($this instanceof Player){
-			$this->dataPacket($pk);
+			$effect->add($this, false);
 		}
 
 		$this->effects[$effect->getId()] = $effect;
-		
-		$this->sendMetadata($this->hasSpawned);
-		if($this instanceof Player){
-			$this->sendMetadata($this);
-		}
 	}
 
 	/**
@@ -356,12 +369,42 @@ abstract class Entity extends Location implements Metadatable{
 
 		$this->namedtag->FallDistance = new Float("FallDistance", $this->fallDistance);
 		$this->namedtag->Fire = new Short("Fire", $this->fireTicks);
-		$this->namedtag->Air = new Short("Air", $this->airTicks);
+		$this->namedtag->Air = new Short("Air", $this->getDataProperty(self::DATA_AIR));
 		$this->namedtag->OnGround = new Byte("OnGround", $this->onGround == true ? 1 : 0);
 		$this->namedtag->Invulnerable = new Byte("Invulnerable", $this->invulnerable == true ? 1 : 0);
+
+		if(count($this->effects) > 0){
+			$effects = [];
+			foreach($this->effects as $effect){
+				$effects[$effect->getId()] = new Compound($effect->getId(), [
+					"Id" => new Byte("Id", $effect->getId()),
+					"Amplifier" => new Byte("Amplifier", $effect->getAmplifier()),
+					"Duration" => new Int("Duration", $effect->getDuration()),
+					"Ambient" => new Byte("Ambient", 0),
+					"ShowParticles" => new Byte("ShowParticles", $effect->isVisible() ? 1 : 0)
+				]);
+			}
+
+			$this->namedtag->ActiveEffects = new Enum("ActiveEffects", $effects);
+		}else{
+			unset($this->namedtag->ActiveEffects);
+		}
 	}
 
-	protected abstract function initEntity();
+	protected function initEntity(){
+		if(isset($this->namedtag->ActiveEffects)){
+			foreach($this->namedtag->ActiveEffects->getValue() as $e){
+				$effect = Effect::getEffect($e["Id"]);
+				if($effect === null){
+					continue;
+				}
+
+				$effect->setAmplifier($e["Amplifier"])->setDuration($e["Duration"])->setVisible($e["ShowParticles"] > 0);
+
+				$this->addEffect($effect);
+			}
+		}
+	}
 
 	/**
 	 * @return Player[]
@@ -376,31 +419,42 @@ abstract class Entity extends Location implements Metadatable{
 	public function spawnTo(Player $player){
 		if(!isset($this->hasSpawned[$player->getId()]) and isset($player->usedChunks[Level::chunkHash($this->chunk->getX(), $this->chunk->getZ())])){
 			$this->hasSpawned[$player->getId()] = $player;
-			foreach($this->effects as $effect){
-				$pk = new MobEffectPacket();
-				$pk->eid = $this->getId();
-				$pk->effectId = $effect->getId();
-				$pk->amplifier = $effect->getAmplifier();
-				$pk->particles = $effect->isVisible();
-				$pk->duration = $effect->getDuration();
-				$pk->eventId = MobEffectPacket::EVENT_ADD;
-				
-				$player->dataPacket($pk);
-			}
+		}
+	}
+
+	public function sendPotionEffects(Player $player){
+		foreach($this->effects as $effect){
+			$pk = new MobEffectPacket();
+			$pk->eid = $this->getId();
+			$pk->effectId = $effect->getId();
+			$pk->amplifier = $effect->getAmplifier();
+			$pk->particles = $effect->isVisible();
+			$pk->duration = $effect->getDuration();
+			$pk->eventId = MobEffectPacket::EVENT_ADD;
+
+			$player->dataPacket($pk);
 		}
 	}
 
 	/**
-	 * @param Player[]|Player $player
+	 * @deprecated
 	 */
 	public function sendMetadata($player){
+		$this->sendData($player);
+	}
+
+	/**
+	 * @param Player[]|Player $player
+	 * @param array $data Properly formatted entity data, defaults to everything
+	 */
+	public function sendData($player, array $data = null){
 		if($player instanceof Player){
 			$player = [$player];
 		}
 
 		$pk = new SetEntityDataPacket();
 		$pk->eid = $this->id;
-		$pk->metadata = $this->getData();
+		$pk->metadata = $data === null ? $this->dataProperties : $data;
 		Server::broadcastPacket($player, $pk);
 	}
 
@@ -588,7 +642,7 @@ abstract class Entity extends Location implements Metadatable{
 		$isPlayer = $this instanceof Player;
 
 		if($this->dead === true){
-			$this->effects = [];
+			$this->removeAllEffects();
 			$this->despawnFromAll();
 			if(!$isPlayer){
 				$this->close();
@@ -1380,7 +1434,67 @@ abstract class Entity extends Location implements Metadatable{
 		}
 	}
 
-	abstract public function getData();
+	/**
+	 * @param int   $id
+	 * @param int   $type
+	 * @param mixed $value
+	 */
+	public function setDataProperty($id, $type, $value){
+		$this->dataProperties[$id] = [$type, $value];
+
+		$targets = $this->hasSpawned;
+		if($this instanceof Player){
+			$targets[] = $this;
+		}
+
+		$this->sendData($targets, [$id => $this->dataProperties[$id]]);
+	}
+
+	/**
+	 * @param int $id
+	 *
+	 * @return mixed
+	 */
+	public function getDataProperty($id){
+		return isset($this->dataProperties[$id]) ? $this->dataProperties[$id][1] : null;
+	}
+
+	/**
+	 * @param int $id
+	 *
+	 * @return int
+	 */
+	public function getDataPropertyType($id){
+		return isset($this->dataProperties[$id]) ? $this->dataProperties[$id][0] : null;
+	}
+
+	/**
+	 * @param int  $propertyId;
+	 * @param int  $id
+	 * @param bool $value
+	 */
+	public function setDataFlag($propertyId, $id, $value = true, $type = self::DATA_TYPE_BYTE){
+		if($this->getDataFlag($propertyId, $id) !== $value){
+			$flags = (int) $this->getDataProperty($propertyId);
+			$flags ^= 1 << $id;
+			$this->setDataProperty($propertyId, $type, $flags);
+		}
+	}
+
+	/**
+	 * @param int $propertyId
+	 * @param int $id
+	 *
+	 * @return bool
+	 */
+	public function getDataFlag($propertyId, $id){
+		return (((int) $this->getDataProperty($propertyId)) & (1 << $id)) > 0;
+	}
+
+	/**
+	 * @deprecated
+	 */
+	public function getData(){}
 
 	public function __destruct(){
 		$this->close();
diff --git a/src/pocketmine/entity/FallingSand.php b/src/pocketmine/entity/FallingSand.php
index 51b91a169..fff4229bd 100644
--- a/src/pocketmine/entity/FallingSand.php
+++ b/src/pocketmine/entity/FallingSand.php
@@ -50,6 +50,7 @@ class FallingSand extends Entity{
 	public $canCollide = false;
 
 	protected function initEntity(){
+		parent::initEntity();
 		if(isset($this->namedtag->TileID)){
 			$this->blockId = $this->namedtag["TileID"];
 		}elseif(isset($this->namedtag->Tile)){
diff --git a/src/pocketmine/entity/Human.php b/src/pocketmine/entity/Human.php
index c2e3bd6a0..dcb28590e 100644
--- a/src/pocketmine/entity/Human.php
+++ b/src/pocketmine/entity/Human.php
@@ -24,6 +24,7 @@ namespace pocketmine\entity;
 use pocketmine\inventory\InventoryHolder;
 use pocketmine\inventory\PlayerInventory;
 use pocketmine\item\Item as ItemItem;
+use pocketmine\math\Vector3;
 use pocketmine\nbt\NBT;
 use pocketmine\nbt\tag\Byte;
 use pocketmine\nbt\tag\Compound;
@@ -37,6 +38,11 @@ use pocketmine\utils\TextFormat;
 
 class Human extends Creature implements ProjectileSource, InventoryHolder{
 
+	const DATA_PLAYER_FLAG_SLEEP = 1;
+
+	const DATA_PLAYER_FLAGS = 16;
+	const DATA_PLAYER_BED_POSITION = 17;
+
 	protected $nameTag = "TESTIFICATE";
 	/** @var PlayerInventory */
 	protected $inventory;
@@ -52,6 +58,9 @@ class Human extends Creature implements ProjectileSource, InventoryHolder{
 
 	protected function initEntity(){
 
+		$this->setDataFlag(self::DATA_PLAYER_FLAGS, self::DATA_PLAYER_FLAG_SLEEP, false);
+		$this->setDataProperty(self::DATA_PLAYER_BED_POSITION, self::DATA_TYPE_POS, [0, 0, 0]);
+
 		$this->inventory = new PlayerInventory($this);
 		if($this instanceof Player){
 			$this->addWindow($this->inventory, 0);
@@ -186,23 +195,6 @@ class Human extends Creature implements ProjectileSource, InventoryHolder{
 		}
 	}
 
-	public function getData(){ //TODO
-		$flags = 0;
-		$flags |= $this->fireTicks > 0 ? 1 : 0;
-		$flags |= $this->hasEffect(Effect::INVISIBILITY) ? 1 << 5 : 0;
-		//$flags |= ($this->crouched === true ? 0b10:0) << 1;
-		//$flags |= ($this->inAction === true ? 0b10000:0);
-		$d = [
-			0 => ["type" => 0, "value" => $flags],
-			1 => ["type" => 1, "value" => $this->airTicks],
-			3 => ["type" => 0, "value" => $this->hasEffect(Effect::INVISIBILITY) ? 0 : 1],
-			16 => ["type" => 0, "value" => 0],
-			17 => ["type" => 6, "value" => [0, 0, 0]],
-		];
-
-		return $d;
-	}
-
 	public function close(){
 		if(!$this->closed){
 			if(!($this instanceof Player) or $this->loggedIn){
diff --git a/src/pocketmine/entity/Item.php b/src/pocketmine/entity/Item.php
index 2fd58b23c..d73f6cc47 100644
--- a/src/pocketmine/entity/Item.php
+++ b/src/pocketmine/entity/Item.php
@@ -52,6 +52,8 @@ class Item extends Entity{
 	public $canCollide = false;
 
 	protected function initEntity(){
+		parent::initEntity();
+
 		$this->setMaxHealth(5);
 		$this->setHealth($this->namedtag["Health"]);
 		if(isset($this->namedtag->Age)){
diff --git a/src/pocketmine/entity/Living.php b/src/pocketmine/entity/Living.php
index 0370b0c0a..ac2413372 100644
--- a/src/pocketmine/entity/Living.php
+++ b/src/pocketmine/entity/Living.php
@@ -46,6 +46,8 @@ abstract class Living extends Entity implements Damageable{
 	protected $invisible = false;
 
 	protected function initEntity(){
+		parent::initEntity();
+
 		if(isset($this->namedtag->HealF)){
 			$this->namedtag->Health = new Short("Health", (int) $this->namedtag["HealF"]);
 			unset($this->namedtag->HealF);
@@ -180,15 +182,16 @@ abstract class Living extends Entity implements Damageable{
 
 		if($this->dead !== true and $this->isInsideOfWater()){
 			$hasUpdate = true;
-			$this->airTicks -= $tickDiff;
-			if($this->airTicks <= -20){
-				$this->airTicks = 0;
+			$airTicks = $this->getDataProperty(self::DATA_AIR) - $tickDiff;
+			if($airTicks <= -20){
+				$airTicks = 0;
 
 				$ev = new EntityDamageEvent($this, EntityDamageEvent::CAUSE_DROWNING, 2);
 				$this->attack($ev->getFinalDamage(), $ev);
 			}
+			$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, $airTicks);
 		}else{
-			$this->airTicks = 300;
+			$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, 300);
 		}
 
 		if($this->attackTime > 0){
diff --git a/src/pocketmine/entity/PrimedTNT.php b/src/pocketmine/entity/PrimedTNT.php
index e4df9d954..55f5f97c5 100644
--- a/src/pocketmine/entity/PrimedTNT.php
+++ b/src/pocketmine/entity/PrimedTNT.php
@@ -45,6 +45,8 @@ class PrimedTNT extends Entity implements Explosive{
 	public $canCollide = false;
 
 	protected function initEntity(){
+		parent::initEntity();
+
 		if(isset($this->namedtag->Fuse)){
 			$this->fuse = $this->namedtag["Fuse"];
 		}else{
diff --git a/src/pocketmine/entity/Projectile.php b/src/pocketmine/entity/Projectile.php
index c155f7b73..7c7547767 100644
--- a/src/pocketmine/entity/Projectile.php
+++ b/src/pocketmine/entity/Projectile.php
@@ -40,6 +40,8 @@ abstract class Projectile extends Entity{
 	private $hadCollision = false;
 
 	protected function initEntity(){
+		parent::initEntity();
+
 		$this->setMaxHealth(1);
 		$this->setHealth(1);
 		if(isset($this->namedtag->Age)){
@@ -52,17 +54,6 @@ abstract class Projectile extends Entity{
 		return $entity instanceof Living and !$this->onGround;
 	}
 
-	public function getData(){
-		$flags = 0;
-		$flags |= $this->fireTicks > 0 ? 1 : 0;
-
-		return [
-			0 => ["type" => 0, "value" => $flags],
-			1 => ["type" => 1, "value" => $this->airTicks],
-			16 => ["type" => 0, "value" => 0] //Is critical
-		];
-	}
-
 	public function saveNBT(){
 		parent::saveNBT();
 		$this->namedtag->Age = new Short("Age", $this->age);
diff --git a/src/pocketmine/entity/Villager.php b/src/pocketmine/entity/Villager.php
index 5c6f8b74c..0ba3c4979 100644
--- a/src/pocketmine/entity/Villager.php
+++ b/src/pocketmine/entity/Villager.php
@@ -68,21 +68,6 @@ class Villager extends Creature implements NPC, Ageable{
 		parent::spawnTo($player);
 	}
 
-	public function getData(){ //TODO
-		$flags = 0;
-		$flags |= $this->fireTicks > 0 ? 1 : 0;
-		//$flags |= ($this->crouched === true ? 0b10:0) << 1;
-		//$flags |= ($this->inAction === true ? 0b10000:0);
-		$d = [
-			0 => ["type" => 0, "value" => $flags],
-			1 => ["type" => 1, "value" => $this->airTicks],
-			16 => ["type" => 0, "value" => 0],
-			17 => ["type" => 6, "value" => [0, 0, 0]],
-		];
-
-		return $d;
-	}
-
 	/**
 	 * Sets the villager profession
 	 *
diff --git a/src/pocketmine/entity/Zombie.php b/src/pocketmine/entity/Zombie.php
index 1b3d7fb27..a20670578 100644
--- a/src/pocketmine/entity/Zombie.php
+++ b/src/pocketmine/entity/Zombie.php
@@ -56,21 +56,6 @@ class Zombie extends Monster{
 		parent::spawnTo($player);
 	}
 
-	public function getData(){ //TODO
-		$flags = 0;
-		$flags |= $this->fireTicks > 0 ? 1 : 0;
-		//$flags |= ($this->crouched === true ? 0b10:0) << 1;
-		//$flags |= ($this->inAction === true ? 0b10000:0);
-		$d = [
-			0 => ["type" => 0, "value" => $flags],
-			1 => ["type" => 1, "value" => $this->airTicks],
-			16 => ["type" => 0, "value" => 0],
-			17 => ["type" => 6, "value" => [0, 0, 0]],
-		];
-
-		return $d;
-	}
-
 	public function getDrops(){
 		$drops = [
 			ItemItem::get(ItemItem::FEATHER, 0, 1)
diff --git a/src/pocketmine/utils/Binary.php b/src/pocketmine/utils/Binary.php
index a948a4e43..9e6ba28e9 100644
--- a/src/pocketmine/utils/Binary.php
+++ b/src/pocketmine/utils/Binary.php
@@ -23,6 +23,7 @@
  * Various Utilities used around the code
  */
 namespace pocketmine\utils;
+use pocketmine\entity\Entity;
 
 /**
  * WARNING: This class is available on the PocketMine-MP Zephir project.
@@ -88,32 +89,32 @@ class Binary{
 	public static function writeMetadata(array $data){
 		$m = "";
 		foreach($data as $bottom => $d){
-			$m .= chr(($d["type"] << 5) | ($bottom & 0x1F));
-			switch($d["type"]){
-				case 0:
-					$m .= self::writeByte($d["value"]);
+			$m .= chr(($d[0] << 5) | ($bottom & 0x1F));
+			switch($d[0]){
+				case Entity::DATA_TYPE_BYTE:
+					$m .= self::writeByte($d[1]);
 					break;
-				case 1:
-					$m .= self::writeLShort($d["value"]);
+				case Entity::DATA_TYPE_SHORT:
+					$m .= self::writeLShort($d[1]);
 					break;
-				case 2:
-					$m .= self::writeLInt($d["value"]);
+				case Entity::DATA_TYPE_INT:
+					$m .= self::writeLInt($d[1]);
 					break;
-				case 3:
-					$m .= self::writeLFloat($d["value"]);
+				case Entity::DATA_TYPE_FLOAT:
+					$m .= self::writeLFloat($d[1]);
 					break;
-				case 4:
-					$m .= self::writeLShort(strlen($d["value"])) . $d["value"];
+				case Entity::DATA_TYPE_STRING:
+					$m .= self::writeLShort(strlen($d[1])) . $d[1];
 					break;
-				case 5:
-					$m .= self::writeLShort($d["value"][0]);
-					$m .= self::writeByte($d["value"][1]);
-					$m .= self::writeLShort($d["value"][2]);
+				case Entity::DATA_TYPE_SLOT:
+					$m .= self::writeLShort($d[1][0]);
+					$m .= self::writeByte($d[1][1]);
+					$m .= self::writeLShort($d[1][2]);
 					break;
-				case 6:
-					$m .= self::writeLInt($d["value"][0]);
-					$m .= self::writeLInt($d["value"][1]);
-					$m .= self::writeLInt($d["value"][2]);
+				case Entity::DATA_TYPE_POS:
+					$m .= self::writeLInt($d[1][0]);
+					$m .= self::writeLInt($d[1][1]);
+					$m .= self::writeLInt($d[1][2]);
 					break;
 			}
 		}
@@ -140,29 +141,29 @@ class Binary{
 			$bottom = $b & 0x1F;
 			$type = $b >> 5;
 			switch($type){
-				case 0:
+				case Entity::DATA_TYPE_BYTE:
 					$r = self::readByte($value{$offset});
 					++$offset;
 					break;
-				case 1:
+				case Entity::DATA_TYPE_SHORT:
 					$r = self::readLShort(substr($value, $offset, 2));
 					$offset += 2;
 					break;
-				case 2:
+				case Entity::DATA_TYPE_INT:
 					$r = self::readLInt(substr($value, $offset, 4));
 					$offset += 4;
 					break;
-				case 3:
+				case Entity::DATA_TYPE_FLOAT:
 					$r = self::readLFloat(substr($value, $offset, 4));
 					$offset += 4;
 					break;
-				case 4:
+				case Entity::DATA_TYPE_STRING:
 					$len = self::readLShort(substr($value, $offset, 2));
 					$offset += 2;
 					$r = substr($value, $offset, $len);
 					$offset += $len;
 					break;
-				case 5:
+				case Entity::DATA_TYPE_SLOT:
 					$r = [];
 					$r[] = self::readLShort(substr($value, $offset, 2));
 					$offset += 2;
@@ -171,7 +172,7 @@ class Binary{
 					$r[] = self::readLShort(substr($value, $offset, 2));
 					$offset += 2;
 					break;
-				case 6:
+				case Entity::DATA_TYPE_POS:
 					$r = [];
 					for($i = 0; $i < 3; ++$i){
 						$r[] = self::readLInt(substr($value, $offset, 4));
@@ -183,7 +184,7 @@ class Binary{
 
 			}
 			if($types === true){
-				$m[$bottom] = ["value" => $r, "type" => $type];
+				$m[$bottom] = [$r, $type];
 			}else{
 				$m[$bottom] = $r;
 			}