The great things about this spell are:
1: It rips through stone skin like nothing (which means alot considering that's usually one of the first protective spells a mage will cast)
2: I BELIEVE it bypasses most spell protections due to the fact that it can pass from 1 person to another so I THINK it is treated somewhat like an area effect spell. I have never seen it (to my knowledge) stopped by anything outside of dispel magic or the spell expiring. It may not work on dragons?
3: It effects up to 6 people (as large or larger than most enemy parties you encounter)
4: It causes all spells of the victim to fail making wizards defenseless
5: It doesn't effect your own party members! Which allows the fighters of the party to run in and hack and slash.
6: It bypasses armorclass so 1 damage per round is dealt no matter what!
7: Has the potential to make enemies run away.
8: No saving throw vs damage or effects.
9: The range is "Sight of caster", which means your spellcaster is easier to protect (or have run away).
10: The level of the spell isn't too high so it can be obtained rather quickly.
Not sure how obvious everything I've written here is.. I dunno why but in my latest trip through BG2 I have found this spell EXTREMELY useful. Jahiera probably cast it more than anything else. I don't think I had it available in my last game, but I was really surprised at how nice of a spell it is.
Anyway..