Need a monster for an ancient research facility.

My fellow DMs, or players with creative ideas, I am looking for a creature to place in or near a ln ancient research facility, as the title suggests. Here's a bit more info to help you decide.

The facility itself was dedicated to making magics or magical technologies to defend against tyrant celestial (gods). The facility itself is located on the edge of a desert region, within visual distance of a World Tree. Currently the facility isn't connected to the World Tree in any way bur such details can be rewritten as needed.

The region that the facility is in has since been converted to a region known as the Sun Tyrants Scourge, a region that is constantly battered by the wrath of Surtr, leading to phenomena like living flame, scarabs made of obsidian glass, and deserts made entirely of glass which shifts between states of solidity.

Anyways, I think thats the most important info. If you have any questions or ideas, feel free to leave them in the comments below. I'm mostly looking for a guardian type creature. Not necessarily hostile, but a threat if provoked.