I've started preparations to GM Doomsday Dawn; and in When the Stars Go Dark, page 91, is a Mind Quake hazard that has a Stealth DC 45.
According to the Game Mastering guide in the rulebook for level 17 characters the highest DC (Extreme) is 43 (for something that should still plausibly be reachable).
DC 45 is really high, especially on a check like Perception. There is relatively little chance opportunity to improve Perception on a character (almost all are stuck on Expert or less) and even a character that focuses on Wisdom won't make that check on a natural 20 unless she also has an item equipped that grants an item bonus to Perception.
Even the end boss fight Ramlock has lower DCs the highest being AC at 43 (and attacks have a bigger list of ways to increase the odds). And the best offensive DCs (spells) that he throws are at DC 41. How did he create a DC 45 hazard? It seems a really unreasonable and out-of-depth.
Ah. Thanks a lot, that goes some way of explaining. But not entirely: the trap is not a true mind quake; but a facsimile created by Ramlock.