Huh, wrack? Powerful?
First he needs to spend almost an entire turn casting it, using around 1/4th or 1/5th of his magic points for the day, then everybody he targets need to take an opposed resilience test meaning most warriors will be testing off their best (or second best) defensive score, and if they succeed nothing happens to them.
Then you need to keep concentration on the spell to cause damage to random hit locations every CA, which usually means it'll take at least 4-5 CA (since you need to hit the same location 2-3 times if your damage is not insanely high) to take down your targets with this spell.
This is 2-3 rounds where everybody you targeted will be peppering you with arrows, swordblows, thrown rocks and insults.
Instead you could have used 3 magic points to turn the entire party into bears or slaargs or whatever combat form you prefer. Then waltz over there and beat your opponents to a bloody pulp with your 1d10 damage modifier.
Or you could have used Teleport offensively, teleporting all but one guy far away from the combat and then you could beat up that one guy. If they save against that spell they still lose a CA to evade. If you want to keep them out of the combat for longer, you could keep up concentration, and teleport them to where-ever you want them to be, and thus make their movement almost meaningless.
If you want to use something that is resisted by resilience, as Dan pointed out, Palsy is much better. If you have 70% or more in your grimoire, one palsy getting through makes the enemy completely unconscious. And the spell is autonomous, so you can cast it, and then get out your weapons and go over there and kill them (or run away and have your minions do it).
All in all I find Wrack one of the weakest sorcery spells. But apart from Palsy, I find most "only offensive" spells in Legend to be mediocre. With a possible exception of Hinder as an autonomous teleport.
