Pretty simple, static enemies to the south, returning nuisance, and a big mini boss, and a really bad boss.
Waking the boss has potential to bust the entire thing. Warning in goblin.
Original:
The adventurers hacked their way through the skeletons and the traps, and eventually chased off the Quasit guarding the tomb. They waked the sleeping Dragon Priest, and fought him down.
Present:
The necromancy has sunken deep into the foundations around the tomb, and it keeps animating new skeletons. Even the old Dragon Priest has been re-animated as a skeleton. But they are leader-less and just wander around in their territory and attacks anything that enters.
When the Hobgoblins moved in, their territory was haunted by the undead remains of the previous leader of the goblins, and after much fighting and work, they managed to subdue him but not kill him, so their shaman had it sealed in the tomb at the undead territory, using the remains of the enchantments over the Dragon Priest's tomb to make the undead thing rest.
The <thing> if released will take control over all nearby skeletons, and march on anything alive in the dungeon. It is sentinent but insane, and can only be negotiated with so far.
kobold, goblin, hobgoblin, human skeletons.
Randomly make some “Bloodsoaked”, self reviving skeletons.
Troll skeleton, with damaged attacks (arm+head)