All you need is a coercer in grp and get him to channel when you get to 0%.
Asking people to give you mana when you use it is kinda defeating the purpose cause its just gonna get drained away. Your better off asking for feeds 30sec after it is down or better yet wait till you use it twice and get to 0 % and then get channeled to 90%

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I tank raids consitently and i spam the shit out of adren... doesnt matter what HP im currently at.... If im tanking any sort of orange raid name im spamming the shit out of adren. And with a shaman in grp you should have him spamming ROA on you too so that its castable again 30 secs after its gone.... ROA+Adren on for 32 secs.... then 2 mit buffs + hold rage for the 30secs downtime of adren... then ROA+Adren rince repeat = in my opinon the best dammage avoidance in game.