bummzack has the correct answer to your question, but I wanted to add another solution.
I always bring along a merc - I prefer the act 2 nightmare merc with holy freeze aura - and move him around to take out the dolls. The mercs are (or were, last time I played) immune to the dolls' damage, and with proper gear can take them out quickly.
Since mercs can use ethereal weapons/armor without them degrading, it is possible to rather cheaply make some stunningly high damage weapons/armor for them. I tend to favor the runeword with Meditation aura (Insight, Ral + Tir + Tal + Sol), for the high damage and mana regen. Though at higher levels and better gear, mana regen becomes less important.
Be aware that it is lethal to teleport into a pack of dolls, though, because the merc can kill a doll quickly, and with you standing next to him, you will get hurt.
Lastly, of course, I have to impart my favorite gem of wisdom: The best way to not get hurt is to not get hit. Some enemies are best left alone. Dolls are one such enemy.