Was on my map ... the main undead area of the Cooling Chambers is a large cavern with a lake in the middle. Circling the outside of the cavern is a tunnel with branches that end in small rooms. Clockwise around the cavern, Shrieking Death is the second small room, towards the SE portion of the cavern. The Frostguard ring is the common drop, often with one of the clays but not always. After about ten kills, she has dropped the aug three times.
Every one of these small rooms can spawn a named. Every one that I've camped has a wanderer. Every one that I've camped has a safe spot in the room, although that safe spot can be very, very small.
The undead are social but have a short aggro range.
Forgot to add ... the PH is a banshee (a_wailing_banshee??). There's no need to clear the entire room to safely fight the named. You can kill one static spawn at the back of the room and the wanderer, and then you have plenty of space and time to fight the named. If you wanted to take a chance, you could even skip the wanderer and pull to the back of the room after killing the static. Most of the time, the roamer doesn't even get to the back of the room before he turns and wanders back out into the tunnels.
Update: After about 15 kills, only dropped aug three times and only dropped leg clay three times. She spawns very frequently (have had three in a row twice).