Vampire plugin

This plugin will mirror back damage as health to attacker. But i can't find any damage event. And how to get an amount of damage that attacker did?

PHP:

public function onDamage(EntityDamageEvent $event){
$player = $event->getEntity();
$damage = $event->getDamage();
if($event instanceof EntityDamageByEntityEvent){
$vampire = $event->getDamager();
if($player instanceof Player){
if($vampire instanceof Player){
if($vampire->hasPermission("Vampire.vampire")){
$vampire->setHealth($killer->getHealth() + $damage));
}}}}}


Should work but I'm not sure

At last line $killer is undefined,use $vampire instead

where is it defined at?

Over there!

Yea sorry, it was a copied code and I didn't see that one!