CierraShore:

The Auras do seem to stack. For Retribution Aura I have 1 @ 35% and 3 @ 41%. For Dmg Aura I have 1 @ 30 Dmg, 2 @ 42 Dmg, 1 @ 48 Dmg, and 2 at 54 Dmg. For Heal Aura I have 2 @ 0.225 per sec.
In the Hall Of Echoes battles with Charon, Marius, Sassan, Amdusias, Liaken, Razakel, Lady Kara, Lord John, and Ba'al my health bar never even moved.

A 2nd time through will be to concentrate even more on those Auras. Just don't know if I can put up with the moving platforms again though... horsey