Talk:Spell vamp/@comment-91.115.164.50-20111117003645/@comment-4626635-20111227024426

The instant damage from Teemo's E is an on-hit effect and does not proc spell vamp. However, the damage over time will proc spell vamp. (100%)

Cho'Gath's E (Vorpal Spikes, I believe) isn't a traditional on-hit effect (like Madred's Bloodrazor, which deals magic damage on basic attacks), but it deals damage to multiple targets, so it will benefit from 33% of Cho'Gath's spell vamp.