Chain Critical
After parry/evade an enemy's attack, you have x% to instant kill a creep or inflict a great amount of damage (maybe base on main attribute) to bosses. After finish that attack, if there are other enemies, you can continue killing them instantly by pressing a hotkey (if this is impossible to do, give this ability another y% to continue the chain critical, but make it balance). This chain can continue as long as there are still enemies left nearby.