Onyx Deer

Large Monstrosity, unaligned

Armor Class 14 (natural armor)
Hit Points 76 (9d10 + 27)
Speed 40 ft.

19 (+4) 15 (+2) 17 (+3) 5 (-3) 12 (+1) 13 (+1)

Skills Perception +3
Condition Immunities petrified
Senses darkvision 60 ft., passive Perception 13
Languages understands Sylvan but can’t speak
Challenge 4 (1,100 XP)

Special Traits

  • Keen Smell. The onyx deer has advantage on Wisdom (Perception) checks that rely on smell.
  • Onyx Bite. Creatures bitten by an onyx deer must succeed on a Constitution saving throw or slowly begin to turn into onyx (included in the attack).


  • Multiattack. The onyx deer makes four attacks: one bite, one gore, and two with its hooves.
  • Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage and the creature must make a DC 14 Constitution saving throw. On a failed save, the creature magically begins to turn to onyx and is restrained. It must repeat the saving throw at the end of its next turn. On a success, the effect ends. On a failure, the creature is petrified in onyx until freed by a greater restoration spell or other magic.
  • Gore. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (1d10 + 4) piercing damage.
  • Hooves. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) slashing damage.
  • Bellow (Recharge 5-6). The onyx deer unleashes a rumbling bellow. Each creature that is within 60 feet of the onyx deer and able to hear it must succeed on a DC 14 Wisdom saving throw or be frightened for 1 minute. The frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.


This creature looks like a deer about 5 feet tall at the shoulders with a dark-brown head and chest changing to light brown on the rest of its body.

A large white patch is prevalent across its back and rump. It has huge antlers at least as wide as a typical human is tall.

Other than being larger than most common deer, an onyx deer resembles its (thought to be distant) lesser cousin. These creatures are found in temperate and warm forested lands in the same general habitat as their normal counterparts though onyx deer do not associate with ordinary deer. Onyx deer are herd animals, congregating in groups of up to 20 individuals. Among the adults, the males outnumber the females by nearly a 2-to-1 ratio. Young (called does) make up the rest of the herd (their total number usually equals the number of adults in the herd).

Mating season for onyx deer comes in the fall. During this time males within the herd often clash with one another. Such clashes see the animals square off and charge headlong into each other crashing their antlers together and slashing with their sharp hooves. When one falls, the battle ends. The loser of the battle usually survives, but always leaves the herd.

Females give birth to 1d3 young in the early summer months.

Onyx deer stand 5 to 6 feet tall at the shoulder and weigh more than 800 pounds.

Onyx deer are generally passive creatures and only attack when threatened or when their herd is threatened. If a herd is molested, both male and female onyx deer defend the young does to the death. An onyx deer begins combat by releasing a loud bellow in an attempt to scare off any would-be attackers.

Those who stand their ground are met with either a gore attack and hooves or a ferocious bite and hooves. The bite of an onyx deer transforms the wound and flesh surrounding it into a gem-like stone that resembles onyx.

Section 15: Copyright Notice

Tome of Horrors © 2018, Frog God Games, LLC; Authors: Kevin Baase, Erica Balsley, John “Pexx” Barnhouse, Christopher Bishop, Casey Christofferson, Jim Collura, Andrea Costantini, Jayson ‘Rocky’ Gardner, Zach Glazar, Meghan Greene, Scott Greene, Lance Hawvermale, Travis Hawvermale, Ian S. Johnston, Bill Kenower, Patrick Lawinger, Rhiannon Louve, Ian McGarty, Edwin Nagy, James Patterson, Nathan Paul, Patrick N. Pilgrim, Clark Peterson, Anthony Pryor, Greg Ragland, Robert Schwalb, G. Scott Swift, Greg A. Vaughan, and Bill Webb