Key to counter this is to manually build first 5 stacks by chewing healers HP down to 50% then unload IR+Berserk+FS+FC+Infuri+Brutal+FC now with proper EU servers its possible to weave 2-3 oGCD so target needs to be extremely fast with purify. You can pop both IR and Berserk before burst so it makes chewing that HP lil bit faster and it might "hide" you incoming burst from target as popping those before double FC is kinda cliche nowdays(good healers know incoming burst when they see those animations).
Also what comes to skill animations its good to use skills like PB and Venge behind obstacle when fighting against physical job as peoples rarely check you buffs, these skills have really clear animations so when enemy doesnt see those it might give you some advantage. For example when fighting against other tank who pops PB i will start kiting untill it drops off, why would i want to be a retard and kill myself for it? :P
