Lenya brings along Torn and Raner on the first trip. Belaver and Neshi on the second trip. Lylamwyn, Kerwin, and Toriah on the third trip.
Round 1: Lenya, Torn, and Raner arrive in the volcanic wasteland with the Black Tower approximately 100 hundred feet away. They see a couple of dozen undead creatures in the vincinity, moving towards them.
Round 2:
16: 8 Undead charge Raner, Torn, and Lenya (4 attack Torn: 17+6+2=25 hit, 9+6+2=17 miss, 1+ miss, 18+6+2=26 hit, Torn takes 2 negative levels, dmg 4; 2 attack Raner 2+ miss, 16+6+2=24 vs. ac 25 miss; 2 attack Lenya 3+6+2=11 miss, 10+6+2=18 hit, dmg 3 -DR =0, 1 negative level). 16 more undead move to within charge distance.
15: Raner attacks a milky white undead creature, hitting once and missing once (pa10, 19+ hit, 10+3=13 vs. ac 20-2+2=20 miss, dmg 18)
8: Torn (-4, 2 negative levels) swings Fragarach the Sword of Heroes in a blur of motion at the terrible undead (Attacks: 12+, 10+, 7+, 14+, 4+, 11+, 9+, 13+, hitting each of the four undead facing her twice, dmg 24, 18, 27, 25)
7: Lenya (1 negative level) flees the scene, reappearing inside the Outer Fane