Forget Warlords Bloodlust on Yasuo for a minute

At 10 stacks at level 18, Fervor of Battle grants 84 physical damage onhit.

is aroused

Seriously, even early game this is terrifying. He stacks up on Scuttle before walking into lane with 30-40 onhit damage from masteries alone.

On a side note, the numbers ingame do not match those on the masteries screen. The client says that each stack grants 3-8 damage based on level, in game it goes up to 8.4 damage per stack.