Mortal Blow: Your next weapon skill may deal critical damage.
15 second recast, 120 second duration. Allows your next WS to deal critical damage and grants +50% to the critical hit rate of the first hit of your WS*. Can be stacked like boost. Each additional stacked effect adds +5% to the critical hit rate of the next WS.
*Without this restriction we would have Guillotine beating out Quietus and Torcleaver which is a situation that should not exist, so we restrict the enhanced crit rate to the first hit only, all additional hits may critical at the normal base rate.