Ok, not that many, but it sure feels like it. They come in bunches of four, and sometimes more than one bunch at a time.
Nasty critters.
Remind me again what spell(s) protect against them? Not Chaotic Commands, not Exaltion, not the 7th lvl clerical spell.
I've had to be a little inventive. Thankfully I had some anti-magic potions. My best run so far was when I stacked up my mage with one of those potions and all the damaging spells I could memorize, and went on a killing spree. I had the boots of speed so that I could outrun the (hasted) drowned dead and barrow wights back to where my paladin was turning undead.
My lvl 22 bard, when not singing to provide protection, is doing some hefty damage with Mordenkainen's Force Missiles. What a great spell for high-level casters.