So I'm trying to decide on which additional skills to use as a WAR. Flash, Provoke, Featherfoot and Convalescence seem like the obvious choices, but I'm not so sure about the last slot. The only other tanky skills are Mantra (42 PGL) and Awareness (34 GLA). Both have the same cooldown (120s) and duration (15s), so the choice is between a 5% healing increase for myself and nearby allies or nullifying critical chance for myself only. If the number of allies benefitting from Mantra times 5% is greater than the mobs critical hit rate, Mantra would be the better option. Otherwise Awareness would be better for surviving large hits. So I find myself faced with the following questions:

How many allies on average will benefit from Mantra?
How often do mobs critically hit in end game content?
Are there any specific fights where Awareness would be necessary to avoid being one-shot by an attack?