Graveyard on the Cliff
Battlemap
If anything is taken from the alter, the graves open up and Skeletons rise in waves of 8, every 3 rounds to attack the PCs, the skeletons can't open doors.
The open chest below the tree is a Mimic, it will attack anyone who touches it.
The cliffs are 5m high and can be climbed easily using a rope or without a rope passing a DC 14 athletics check.