Creation tree is so lame. If your main is a mage do entropy, spirit healing, and only go into force for the interrupt prevention. Spirit is a tossup, and primal or elemental are okay.
That's the best spec for bosses anyways, and allows for the best utility.
Works for me on hard on bosses, and your hp regen with spirit healer is so fast, as long as he runs away for like 2 seconds, suddenly all his hp is back. However, it feels rather useless because you should be paying enough attention to keep mobs from ganging you anyways, but it helps for that one or two times a fight.
Haste and heroic aura aren't necessary until end game bosses anyways, and even then not really necessary either. Maybe on Nightmare? Idk. Since I fucked up and missed out on the SUPER SECRET boss because I didn't destroy all the books (there's 5, and taking or reading any of them keeps you from the quest) the only major boss left I have is the High Dragon in the next act, or maybe some little ones before then and the final boss.
This is too easy :\
edit: Actually I guess what I'm saying is creation is terrible on anything but nightmare.