I tested 1108 a while back and these are my guesses for how it works:
- The spell has three endroll ranges: 101-120, 120-149, and 150+.
- Within a range, it doesn't matter what the roll is. 150 is as good as 250.
- 101-149 contains the results of the target running to a different room.
- 120-149 contains the results of hesitating briefly.
- 150+ is always either frozen or instant kills.
- The instant kill rate on 150+ is about 20%. It's possible this depends on lore but I couldn't fixskill to test.
- Telepathy lore modifies the thresholds so you can start getting the best results starting from 140-ish endrolls.