I wanted to comment on the statement about nature damage being no good against the undead. That is true, they are immune, as are revenants, and even darkspawn tend to have a slight resistance to it (though I have seen conflicting things on the darkspawn issue). Wild animals, while not immune to nature damage, have high resistance, like around 60%. For a while I stayed away from nature damage for these reasons, but revenants are also immune to ice and rage demons are immune to fire, so elements are always a double edged sword. I have noticed recently that the archdemon's lowest elemental weakness is nature. It does not have the resistances of a normal dragon, in fact, its resistance to ice is higher than it's resistance to fire and I wouldn't suggest spirit or electricity( two of my very favorites) either. It is for this reason that I usually equip alistair with the veshialle towards the end, at least to fight the archdemon. That 2 nature damage is minor, I know, but I also like to bring wynne because I usually teach her stinging swarm, giving me a powerful single spell against the archdemon (nature based). Normally crushing prison and curse of mortality which I tend to teach morrigan, assuming I am not playing as a mage, are my favorite single target spells. The archdemon's spirit resistance makes this inadvisable, though. On a slightly related note, the archdemon's breath attacks do spirit and not fire damage btw.