What does sated do?

It's kind of complicated, but there's a list on this page of on-hit effects and on-attack effects (I didn't know there was a difference until I looked for a page for you.)

http://leagueoflegends.wikia.com/wiki/Sated_Devourer

http://leagueoflegends.wikia.com/wiki/On-hit_effects

On hit effects are things that happen with every autoattack you perform. They are ability/item passives that trigger when you autoattack. Usually when something is an on hit effect, the game will tell you that.

UNIQUE Passive: +15 (+ 15% AP) on hit magic damage

Sated applies On-Hit Effects twice every other autoattack 's Toxic Shot ability is an example of an On-Hit Effect 's Grandmaster's Might thing is an on-hit effect as well. With Sated, he can activate it's third hit every other autoattack instead of every three autos