I've come across a couple of problematic things about the new Diggle behaviour: 1) In Monster Zoo rooms with Diggles, sometimes the Diggles will burrow past the walls of the room into other more or less adjacent parts of the dungeon. This means a lot of tedious backtracking to track down the wayward Diggles. The closest thing I've experienced to this previously is monsters like Wights and Gnomes blinking through doorways or thin walls, but Diggles seem to be able to pass through thicker walls. This whole thing might be working as intended, but I thought I'd point out that runaway Diggles make Zoos way more tedious to finish. 2) Similar to #1, when a squad of Diggles is created for a quest it can get really annoying wandering around or just wasting turns while waiting for them to pop back up. It's a nice touch that burrowed quest Diggles don't have quest tracking icons on the mini-map, but aimless waiting just because the last quest mob decides to vanish for several turns bugs me. Aside from that, 90% of the time the burrowing is loads of fun and a brilliant way to shake things up. I'd really love to know more about the AI side of it (how they decide to burrow/pop up), but in my heart I know there's only one true answer: "Diggles gonna dig."