Right. Start the minific mill of cave adventures, dnd-scale bug-murder, and possibly cannibalism amongst lost wanderers. Or Cloudy and Marble being sexy mud-covered gladiatrixes in the arena of giant rock weevils. Gotta put those rock-powers to use.
Also, wowie, Equestria sure is full of horrible dangerous giant critters. (Or maybe that thing will save them in an odd twist of events that proves me a horrible species-est person. That’d be neat.)
I’m guessing that Anon’s magical presence is what’s driving the beasts to the surface and that thing burrowed through the lake bed to reach him. That would explain the hole, since nothing we’ve seen him do would cause it.
If that’s the case then he’s a beacon for monsters and they’ll be coming from all over to get him.