And I know why. According to tweakDB, every monster in the game has it's HP multiplied by 1.35 per floor, so a Diggle you meet on Floor 3 is meaningfully more HPfull than one you meet on Floor 1. Wizardlands are defined as Floor Zero. That means that the only HP Wizardlands mobs have is their base HP -- not that noticeable when you're facing down Sickly Diggles, but if you go to a DL8+ Wizardlands, you'll notice that you're suddenly one-shotting mobs that used to take you 3-4 turns to take out. I haven't played much with it, but I'm relatively certain that Diggle Hell and Mysterious Portals have this same problem. I don't know what the solution might be, but it probably deserves some attention.