/damage: Hurts entities by an amount, with an optional cause and attacker.
Syntax
<angle brackets> are required, [square brackets] optional. /damage has 2 forms:
/damage <target: selection> <amount: int> [cause: damagecause]
/damage <target: selection> <amount: int> <cause: damagecause> <origin: damageoriginactor> <damager: selection>