You mean Zallanora? That woman isn't immune to time stop!
But she casts "spell trap" as a contingency spell so that's probably why none of your spells are getting through.
Try abi-dalzims or sunfire: it will scorch her with no problem.
and since her first spell is usually Time Stop: cast it with good timing as soon as the nosy wizard does the dimension door.
------------------
Greetings Mortals. My Name Is Wah, Arch Lich Wah.