5 Chars Dungeon Powerleveling Multibox

[Apatheist]

Does that actually work or does it run out of mana before killing things?
[Holy Nova]

It doesn't. Holy nova is incredibly weak in PvE. I see it used is in PvP occasionally, you can use rank 1 to get rogues out of stealth.

If your doing dungeon runs, purley for leveling so nothing high level... Do you NEED a tank or can you overwealm the mobs and bosses with DPS?

All low-mid level dungeons can be tanked by anybody with decent mitigation who can hold agro. No need to spec protection outside of raids. It's more about your gear than your talents. If you look at the warrior protection tree for example, there's nothing past the third tier of talents that increases your survivability. In dungeons it's more important to make sure you're maximizing your threat output so you can clear faster.