Since this is the first mana consuming build I play as a barb, I didn't have a clue that I could just switch to eagle stance... silly me.

Also Overkill has 4 reduced mana cost with each hard skill point spent, so the further I level the less I need to stay in eagle stance and can swap to snakey snake.

Eagle stance to snake stance feels like the turbo mode of this little fella:
I just killed Baal at level 47 with only poison and fire resistances capped, my merc kinda did the work though - exemplar with shark RW in a ethereal brandistock(6).

He's so bad.

By the way, how does overkill work? Can each single axe leech life, have a crushing blow, cause a proc? - Will the number of axes increase my overall proc rates?
Can I do fancy stuff by swapping stances before impact? Like changing to snake before it hits and still cause extra poison damage?
I guess damage is calculated by impact, so I guess "in theory" you could skillswap eagle/snake.