Mixology is a passive bonus to every elixir you Aoc Gold drink (about 20% - 25% increased effectiveness) Endless Healing and Mana potions are as far as I know the only potions so far usable in arenas. They do of course require alchemy as a profession, which will most likely make it the obvious choice for PvP healers. I said it once and I'll say it again, I loathe the idea of prolonging arena matches further, and I don't see how this can benefit it.