As other said, I usually just skipped it after running that dungeon 5+ times.

If you really want to kill them, run in tight circles around the two sprites. You won't get hit by their lightning if you keep moving in tight circles, because spells only hit you if you're still in front of the mob at the end of the cast. Do this until enough of the mobs are dead where you can survive without having to run in circles & look like a spaz.