I looked at origins as what I believe it was: Bioware's own adaptation of D&D mechanics packaged in an upgraded form of NWN (for two obvious reasons: no licensing costs for the source material and mechanics, and a system that makes more sense when you consider you're running it on a computer). In that light, it was a huge upgrade, though melee fighters still remained pretty simplistic. I ran (or am running, rather, as I picked it up again recently) a party with three mages (my blood mage, Morrigan, and Wynne) and Skippy the Paladin as a tank. Blood Wound is possibly the most singularly overpowered spell in the game, causing minor damage over time (well, something like 13 spirit damage every second, for close to ten seconds), but freezing every single enemy in a large area, ignoring friendlies, while being extremely cheap and having a recharge time of only 20 seconds. Blood magic in general is a severely broken "I win" button, allowing obscenely expensive alpha strikes, at which point it gets shut off, and a simple, twenty mana healing spell completely replenishes your health, if you don't just you Blood Sacrifice on the tank, who's still in the process of running towards the enemies you just beat down.
My strategy went:
1) Disable party movement.
2) Fireball to draw aggro on my mage.
3) Run away from party, towards enemies, drawing them all into one cluster.
4) Blood Wound over self.
5) Run back to party, Morrigan casts Affliction Hex on clump of enemies, I cast Fireball.
6) Everything is dead or dying, Skippy the Paladin mops everyone up, if the three mages don't bring everything down with their damage spells first.
Dammit, semi-ninja'd.
That wasn't the perfect tactic, the perfect tactic went:
1.PC casts Blood Wound.
2.Morrigan casts Blood Wound.
3.Wynne casts Blood Wound.
Blood Wound was so broken.