How can you access this spell?  What line is it under?

@Aiel117: It can be found as a quest reward.

It might be a good idea to cap the damage (at, say, 10 * caster level ) -- say a caster can't channel more than that without blowing up.  ("Sacrifice champion to annihilate an enemy / multiple enemies" might be an interesting spell in its own right, though....)

Heh, ya I used it on my magic build civ.  My leader with path of the mage could cast it for 3 mana after the cost reductions from items/traits, and did 4-600 per turn with it.  The weird thing was (and this was 0.85) that even if the spell was resisted, I'd still see damage go up.  A bug?  But coupled with full mana shield, that was just a one person army.  Effective 4k health, and I could dish out that much DPS every round . .crazy stuff.

Flipside, that only happened because I had tons of red equipment, a totally mage spec leader, and didn't use mana on the strategic map, so in a way its balanced since I put everything towards it.  Since it only got that powerful endgame, in a way its a good thing.  If there were more compelling reasons to use mana on the strategic map in my game, I doubt I ever would have gotten the mana pool big enough to really misuse the spell that way.