Talk:Kog'Maw/@comment-10880231-20140419105523/@comment-9771997-20140428055609

If you're doing magic damage, then Spell vamp will give you health. So yes, it works with Spell vamp, but not really that well unless you're fighting some kind of super tank. Say you built 20% spell vamp, you'd be leeching about 1.2% of their max hp before magic resist gets involved (though resists aren't a huge issue for Kog) if you had no AP helping it out but the skill was maxed. Now say you were attacking an enemy champion with 0 MR and exactly 2k hp, you'd leech a grand total of 24 hp per hit. With 500 AP and the skill maxed you'd be leeching 2.2% of their max hp per hit without resists, and that would get you 44 hp on that same 2k health target with 0 MR. With 500 AP your W would be hitting for 11% of their max hp, which is great damage, but unless you're going to stack Spell vamp you're gonna be leeching 1/5th of that (which is where 2.2% came from).

tl;dr: It works, but not well.