attack
This is the preferred way to attack a living entity if you have a living entity as the underlying entity. It will simulate a real attack using Minecraft's damage system. If you do not have a living entity as the underlying entity, it will default to doing 1 damage to the target, and at that point, you should use attack instead.
Beware, this damage uses custom damage which might get reduced somewhat randomly by Minecraft, so test it before using it. Preferably, you should use attack instead, and if you need to modify the damage, you can hijack the damage event and modify the damage amount.
Parameters
target
Target to attack
damage
Damage to deal