The Corrupted Catacombs

From the introduction:

Years ago, after The Great Battle, the dead were laid to rest in a series of catacombs near a baron’s keep. Now the necromancer Lusk has made the catacombs his fortress and sends undead to terrorize the area. The baron offers a reward to anyone that can stop him. Above ground is a sturdy, squat mausoleum with a long staircase inside that leads to the crypts below. All rooms in the catacombs are unlit unless otherwise noted. Pit Traps are 4m deep with spikes at the bottom; the 2x3m floor section will pivot to drop trespassers down and then return to its original position.