Is Dooku getting health and dmg buff?

You basically get your health and damage buff by finishing G12. If you mod him with an offense set, offense cross, crit damage triangle, and a crit chance set, you can get some reasonable damage out of him if you count the double attack. My g11 dooku crits for 8k. That's not huge, but he's basically there for the debuffs he dishes out. Getting counter-stunned can ruin your day quick.