As a warrior, I use this trinket on Kidney Shots, most forms of roots (Frost Nova, Entangling Roots if Pummel is on cooldown etc.), any stun effect that interrupts my adavantage in a fight and all pally stuns.
I don't use this on Cheap Shots, Repentance or Fear (Because warriors have Berserker Rage and Death Wish if you talent for it). It's sometimes hard to know when there's a good oppotunity to use this trinket. From a warrior stand point, I mostly use this on stuns and roots. Getting out of a Kidney Shot interrupts a rogues battle plan altogether, stopping a pally stun prevents "free damage" done to you and stopping all roots gives you another 12-20 seconds of time you beat your opponent to crap.
I don't use this on Cheap Shots, Repentance or Fear (Because warriors have Berserker Rage and Death Wish if you talent for it). It's sometimes hard to know when there's a good oppotunity to use this trinket. From a warrior stand point, I mostly use this on stuns and roots. Getting out of a Kidney Shot interrupts a rogues battle plan altogether, stopping a pally stun prevents "free damage" done to you and stopping all roots gives you another 12-20 seconds of time you beat your opponent to crap.