Looking for monsters for some ruins

Basically I have a series of ruins in a desert. These ruins will contain a coven of hags, one lich and there undead minions. I was wondering if I could get some creature ideas

adjusting desert creatures like Giant Scorpions and the like to withered mummified undead versions of themselves would be fairly thematic.

My question is why are the monsters there, in your story - did the lich bring them, the hags summon them, or were they already there? are they natural squatters (like bears in caves) or are they meant to defend the ruins (like constructs and gelatinous cubes)?

The lich and the hags brought them to the ruins for protection as they do a ritual

ok, so where did they bring them from? if they are swamp hags then crocodiles and giant snapping turtles would make sense, whereas if they are sea hags then giant hermit crabs or other seafaring monsters would be fitting. Also gives the party clues about what they will face - "why are we fighting coastal creatures in the desert?"

The hags are night hags