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.
Speed 40 ft.
Str 19, Dex 15, Con 17, Int 5, Wis 12, Cha 13
Twice per day, an onyx deer can unleash a rumbling bellow that instills fear in any creature within 100 feet that hears it. All creatures in the area must succeed on a DC 14 Will save or be shaken as long as they remain within the area and for 2d4 rounds afterward. A creature that succeeds on its saving throw is immune to the bellow of that onyx deer for 24 hours. The save DC is Charisma-based. Onyx deer are immune to their own bellow and that of other onyx deer.
An onyx deer’s bite deals 1d4 points of Constitution damage against a living creature if it fails a DC 18 Fortitude save. A living creature reduced to Constitution 3 or less transforms into onyx, resembling nothing more than a statue. A stone to flesh spell returns a transformed creature to its original form, though if it was reduced to Constitution 0 by the onyx deer’s bite it immediately dies upon returning to its natural form. The save DC is Constitution-based.
Environment temperate and warm forests
Organization solitary, band (2-5), or herd (6-18)
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.