I have re-skinned many of the monsters from the AD&D Monster Manual & the LFG Core book to fit the aesthetics of the World of WeirthTM.
This adjustment tends to get made on a case-by-case basis, as the need arises in the game. While I do have a Dungeon Style Guide, I have not taken the time to sit down and fully re-imagine the encounter tables on a general basis. Warren at I Cast Light has done an amazing job of showing what can be done with this exercise:
PRINCIPLES: I think I have outlined a few general qualities of monsters in the “Twilight Realms” that might separate it from the standard D&D arrangement above. Examples are given with the Level 1 monsters, but I’ve tried to maintain these core ideas throughout.
First, the “peoples” (Cultist of Yg, The Nameless Legion, & Sailors from Leng) of these dreamlands often bear curses and/or traditions originating from somewhere else not connected to the dungeon now. And although not explicit (but I might make it so later), they have an agenda separate from “sitting around” in the dungeon– they are searching for something. This is much like the PCs.
This is definitely going on my to-do list!
The denizens of the Belowdark, the creatures it spawns, are well-defined after nearly three years of play. This should not be too difficult or time-consuming, as I already have several kinds of maps showing lairs, areas controlled by various factions, and the “common” creatures of various biomes.
Stay tuned, there will be a new tag Weirth Bestiary.