Monster Themes

Gaggles of beasties operate inside a thematic 'space' by being originated from the same source, or something.

Like, why is all this weird stuff happening around Townton? Ah, well, the miners here hit something strange a few years back... The huge amethyst in the strip mine a mile out has given creatures - and people - powers. Some of them look like zombies, or there's hounds that blink in and out of existence, or there's serpents that breathe sleep gas, but it's all from the mineral. They all have purple eyes, too, or crystals in their fur and scales, whatever.

As well, all of the creatures follow certain rules. The amethyst itself is easily shattered, so all of the beasts have thunder damage vulnerability, but are also fireproof or have some weird psychic static around them or whatever.

By tying stuff together you obviate the need to explain away why a CR-appropriate critter is out here. Why did we encounter a Gray Render? Ah, it wasn't a gray render, it was a Thoughtbeast that looked like a gray render.