Or, of course, anyone to get in. Ever.
You know, that doesn't limit the options much. Some. There are those creatures/protections that the wizard could have put on purpose, and those that could have snuck in to set up a home, and those that could have gotten in accidentally, or thinking they could escape, but there are some actual monsters that could have avoided all of those. Not enough to restrict the matter, certainly not enough to prevent its seeming random without more constraints.
I suspect I will jump on my early inspiration of automata, although I may have to slither in some illusions as well to foreshadow something from the very original inspiration. And making the distances inside non-Euclidean will tie into two other elements.
poke, poke, poke.
Still needs time to bake.