Going out on a limb, I think the respawn time is still 7 minutes and Nilbog is estimating you having good odds of seeing him once every 3.3~ hours.
Without getting into any crazy statistics on variation and what not, I calculate you should have a greater then 50% chance of seeing the Undead Grimrot (2% spawn chance) once by the 35th round. At 7 minutes per round, this is just over 4 hours (245 minutes for approx 50.7% chance of Undead Grimrot 1 time).
The math can be misleading tho, it's only a rough guideline. It takes 114 rounds to get the expectation to 90% chance of seeing him. That's 13.3 hours straight, and 10% of people (theoretically) that do it like that still won't have seen him. 99% certainty of seeing him is at round 228 (more then 26.5 hours).
|