Crypts, mausoleums, cemeteries, and other places of the dead have strange dangers and unique risks, beyond undead and necromancy. Below are some example spooky hazards you can find in places like these.
Corpse Oil
Depending on how a corpse is buried and in what manner it decays, it can sometimes turn into a black greasy substance that spills out of a damaged coffin or sarcophagus. This material has a slick oily consistency with a strong odor that is highly flammable.
Corpse oil covers a 10-foot square area. A creature that enters the area or ends its turn there must succeed on a DC 13 Dexterity saving throw or fall prone and be covered in corpse oil.
An effect that deals fire damage will cause the corpse oil to burn for 1 minute before being destroyed. A creature or object affected by burning corpse oil takes 3 (1d6) fire damage at the beginning of each of its turns. A corpse oil fire can be doused by covering it with sand, dirt, or similar material.
Hands of the Dead
Mass graves are often a source of malign spirits and necromantic magic. When these areas are combined with shallow graves, wary travelers can be surprised by sudden grasping limbs.
A patch of hands of the dead covers a 10-foot square area. This area is difficult terrain. A creature that enters the area must succeed on a DC 12 Strength saving throw or be grappled and restrained by clawing undead hands.
A patch of hands of the dead has AC 10, 15 hit points, and is immune to poison damage.
Negative Energy Zone
A zone of negative energy is a place of antilife. Death and decay thrive in such a place where the living are slowly drained of their life force. A negative energy zone is the result of the mixing of powerful chaotic forces.
A zone of negative energy covers a 10-foot cube area or larger. When a creature starts its turn within the area, it accumulates a -1 penalty to ability checks, attack rolls, and saving throws (maximum of -5). Each round a creature starts its turn outside of the area this penalty is reduced by 1 until it fully recovers.
Casting dispel magic using a spell slot of 5th-level or higher on the area destroys the negative energy zone.
Spiteful Rest
Haunted places can sometimes be benign with nothing more than spooky sounds and creepy shadows, but when a creature filled with malice dies it may haunt a space and treat anyone who passes through as responsible for its spite.
A place of spiteful rest covers a 10-foot cube area or larger, most often encompassing a structure, cemetery, or battlefield. A creature that enters the area or starts its turn there must succeed on a DC 14 Dexterity saving throw or take 10 (3d6) bludgeoning damage as loose objects are hurled at it by unseen forces.
Casting dispel evil and good on the area or expending a use of Channel Divinity while within the area cleanses the area of spiteful rest.
Toxic Spores
Spores can be found on decaying corpses or within plants and are expelled into the air when the area is disturbed. Once in the air, they appear as tiny clouds of dust of various colors with particles that sparkle and reflect light. Breathing in these spores can cause a general feeling of sickness and may result in hallucinations.
A cloud of toxic spores covers a 10-foot cube area. A creature that enters the area and inhales spores must make a DC 13 Constitution saving throw or be poisoned for 1 hour.
An effect that deals cold, fire, or radiant damage will destroy a toxic spore cloud.
Umbral Veil
Some areas of darkness seem to defy magic that would normally pierce its veil yet are easily defeated with mundane light. An umbral veil would appear like any other area of darkness when approached with torchlight, but its true nature is revealed with a simple light spell. These phenomena appear when planes of darkness spill out into the material plane, leaving behind a field of bizarre shadow.
An umbral veil can be as small as a 5-foot cube area all the way up to several hundred feet on a side. Mundane light treats this area as normal darkness but light from magical effects or supernatural abilities, such as darkvision, have no effect.
Further Reading
If you’re looking for more hazards, take a look at the aquatic hazards.
Add some undead flavor to your monsters with the flavor of death.
