Small monstrosity, chaotic evil
Armor Class 23
Hit Points 112 (15d6 + 60)
Speed 30 ft., climb 40 ft.,
Saving Throws Dex +10, Cha +11
Skills Acrobatics +10, Perception +7, Stealth +10, Survival +7
Damage Resistances bludgeoning, piercing, and slashing from nonmagical attacks.
Damage Immunities poison
Condition Immunities poisoned
Senses darkvision 30 ft., passive Perception 17
Languages Abyssal, Infernal, understands Common and the languages it knew before it was a yara-ma-yha-who, but can't speak it
Challenge 12 (8,400 XP)
Ambusher. In the first round of combat, the yara-ma-yha-who has advantage on attack rolls against any creature it surprised.
Fiendish Nature. The yara-ma-yha-who adds its Charisma bonus to its AC (included in the calculation).
Magic Resistance. The yara-ma-yha-who has advantage on saving throws against spells and other magical effects.
Nimble Escape. The yara-ma-yha-who can take the disengage or hide action as a bonus action on each of its turns.
Standing Leap. The yara-ma-yha-who's long jump is up to 20 feet and its high jump is up to 10 feet, with or without a running start.
Multiattack. The yara-ma-yha-who makes two slam attacks.
Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: X (1d6 + 2) bludgeoning damage. The yara-ma-yha-who gains temporary hit points equal to the damage dealt.
Blood Drain. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: X (1d6 + 2) bludgeoning damage and the yara-ma-yha-who grapples the target. Until the grapple ends, the yara-ma-yha-who doesn't attack. Instead, at the start of each of the yara-ma-yha-who's turns, the target loses X (2d6 + 4) hit points due to blood loss. The yara-ma-yha-who regains hit points equal to the damage. Constructs or undead are resistant to the damage received during the grapple.
The yara-ma-yha-who can detach itself by spending 5 feet of its movement. It does this after 4 rounds, the creature drops to 0 hit points, or it has taken 15 damage. A creature, including the target, can use its action to make a DC 16 Athletics check to detach the yara-ma-yha-who. The target dies if is hit points are reduced to 0. A humanoid slain in this way returns as a yara-ma-yha-who the following day.
If the humanoid is Medium, the yara-ma-yha-who may choose to use an action to make a melee attack against the creature it is grappling. If it hits the creature, it is swallowed by the yara-ma-yha-who. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the yara-ma-yha-who, and it takes X (2d6) acid damage at the start of each of the yara-ma-yha-who' turns. A humanoid that dies in this way is regurgitated as a yara-ma-yha-who.
If the yara-ma-yha-who takes 20 damage or more on a single turn from the swallowed creature, the yara-ma-yha-who must succeed on a DC 17 Constitution saving throw at the end of that turn or regurgitate the creature, which falls prone in a space within 15 feet of the yara-ma-yha-who. If the yara-ma-yha-who dies, a swallowed creature is no longer restrained by him and can escape from the corpse by using 5 feet of movement, exiting prone.
Leap. In response to being targeted with a melee attack, the yara-ma-yha-who makes a long jump away from the attacker, imposing disadvantage on the attack and adding 2 to its AC.
Not many people are in the know of what happens when the fiendish essences of the Lower Planes blend with those of the Material Plane. Some know of when fiends and mortals themselves mix, but when the magical energies of the planes blend together, it can result in quite the nasty creature. One such creature is found in the forests of the frontier lands, far from established civilization, preying on those who wander the woods alone.
Bloody Little Beast. The strange monster known as the yara-ma-yha-who is a monstrosity, to say the least: standing just a little taller than a gnome, this monster is a slimy skinned frog-like creature with red skin and hair, if it has any. Its fingers are long and spindly, each tipped with suckers, not unlike those of a frog or gecko. The mouth of the fiend is massive, as wide as the entire body, and has no teeth at all, as well as being able to unhinge its jaw like that of a snake.
This devilish little creature swings through the trees during the day and climbs into the lower reaches of the canopy to sleep when dusk falls. When it finds a lonely creature, primarily children, the yara-ma-yha-who grabs a hold of them and sticks its suckers onto it, usually by the arms, and through them sucks out its blood. If it does not die from this outright, it may choose to swallow them whole and eventually regurgitate them up. Most horrifyingly, those that die from blood loss to a yara-ma-yha-who will rise up again, as a new yara-ma-yha-who.