Two questions regarding stacking.

[DJGravity]

Does the relenless fury rage proc stack with barbarian rage? Also, does the doublestrike stance (from martial epic past life feat) stack with doublestrike from monk wind stance?

[Ultinoob]

I only know about the doublestrike and then not totally. Doublestrike from past lifes stack with doublestrike from items, but i haven't tested it with monk. My guess is that it stacks...

[FuzzyDuck81]

Past life feats should stack with everything, that's kinda the point, so you can make your character more powerful :)

And relentless fury stacks with barbarian rage too, they're different kinds of rages behind the scenes.