Obelisk of many things (5e Trap)
From D&D Wiki
Obelisk of many things
A pillar sits the middle of a room with many magical symbols on each face, some of which resemble glyphs of warding.
The trap is magical by nature, and if you are a wizard, you can attune to it. The various magical abilities depend on who has lain it, and what school of magic they practice. Some abilities have only one use, but others continually activate until turned off. Each obelisk requires a different amount of space to be contained. There are sliding doors leading to them. These doors come down once a group enters the room containing the obelisk, and the last creature to make it through the doorway must make a Dexterity save to avoid the door landing on them. To turn the obelisk off and leave the room, you need to touch the faces of the pillar in a certain pattern.
- The room of silence is a 50 by 50 block(each block is five feet by five feet) room that's empty except for the pillar. You may want an encounter to make use of this room.
- The elemental sniper is a 35 by 35 block room that has spells of various elements flying across it randomly. Depending on level, these deal 1d6, 1d8, 1d10, or 1d12 elemental damage each.
- The tiles of fire is a 15 by 15 block room, and the tiles around the pillar deal 1d6 fire damage once per creature.
- The pillar of conjuration summons various monsters by a magical pulse until the puzzle is solved.
- Mephits summon in groups 1d8 large.
- Skeletons summon in group 1d8 large.
- Ghouls summon in group 1d6 large.
- Zombies summon in group 1d6 large.
- Ghosts summon in group 1d6 large.
- Specters summon in group 1d4 large.