Umi-Bozu

Amphibious. The yokai can breathe air and water.

Amorphous. The yokai can move through a space as narrow as 1 inch wide without squeezing.

Corrosive Form. A creature that touches the yokai or hits it with a melee attack while within 5 feet of it takes 4 (1d8) acid damage. Any nonmagical weapon made of metal or wood that hits the yokai corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls. If its penalty drops to −5, the weapon is destroyed. Nonmagical ammunition made of metal or wood that hits the yokai is destroyed after dealing damage. The yokai can eat through 2-inch-thick, nonmagical wood or metal in 1 round.

Ethereal Sight. The yokai can see 60 feet into the Ethereal Plane when it is on the Material Plane, and vice versa.

Spider Climb. The yokai can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

ACTIONS

Pseudopod. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) bludgeoning damage plus 18 (4d8) acid damage. In addition, nonmagical armor worn by the target is partly dissolved and takes a permanent and cumulative −1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10.

Body Slam (Recharge 6). The yokai stretches its body out and slams down on nearby creatures.  The area of effect of this attack is the Size of the creature and the range is its reach with its pseudopod attack. Each creature in the area must make a DC 13 Dexterity saving throw, taking 7 (2d6) bludgeoning damage on a failed save, or half as much damage on a successful one. The target is also exposed to its corrosive form trait.

Vomit Water (1/Day). The yokai vomits water in a 20-foot line that is 5 feet wide. Each creature in that line must make a DC 13 Dexterity saving throw, taking 14 (4d6) bludgeoning damage on a failed save, or half as much damage on a successful one.

REACTIONS
Catapult Weapon. As a reaction to being hit, the yokai spits out a weapon embedded in its body:

• Catapult Katana. Ranged Weapon Attack: +5 to hit, range 20/40 ft., one target. Hit: 9 (2d8 + 3) slashing damage.

Split. When a yokai that is Medium or larger is subjected to lightning or slashing damage, it splits into two new yokai if it has at least 10 hit points. Each new yokai has hit points equal to half the original pudding’s, rounded down. New yokai are one size smaller than the original yokai.

DESCRIPTION
Ko-umi-bozi, literally “small umi-bozu,” are the resentful souls of samurai who died fighting at sea. They are said to lurk in the waves and ambush passing vessels, making them feared by fishermen, but also reportedly come up onto the shore at times.

Their bodies are made of jelly-like water, and despite their weapons, they attack only weakly. The faintly shining sphere at their core is said to be their vulnerable point, and there are legends of fishermen who successfully drove off attacking Ko-umi-bozu by harpooning this sphere when it happened to be exposed at the right time.

Foul. Any creature, other than an ooze, that starts its turn within 10 feet of The Umi-Bozu must succeed on a DC 21 Constitution saving throw or be poisoned until the start of the creature’s next turn.

Innate Spellcasting. The Umi-Bozu’s spellcasting ability is Charisma (spell save DC 18, +10 to hit with spell attacks). The Umi-Bozu can innately cast the following spells, requiring no material components:

• At will: acid splash (17th level), detect magic
• 3/day each: blight, contagion, gaseous form

Legendary Resistance (3/Day). If The Umi-Bozu fails a saving throw, it can choose to succeed instead.

Magic Resistance. The Umi-Bozu has advantage on saving throws against spells and other magical effects.

Magic Weapons. The Umi-Bozu’s weapon attacks are magical.

Regeneration. The Umi-Bozu regains 20 hit points at the start of its turn. If it takes fire or jade damage, this trait doesn’t function at the start of its next turn. The Umi-Bozu dies only if it starts its turn with 0 hit points and doesn’t regenerate.

Spider Climb. The Umi-Bozu can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

ACTIONS

Multiattack. The Umi-Bozu makes three the tentacle smash attacks.

Tentacle Smash. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 21 (4d6 + 7) bludgeoning damage. Any creature killed by this attack is drawn into The Umi-Bozu’s body, and the corpse is obliterated after 1 minute.

Eject Slime (Recharge 5–6). The Umi-Bozu spews out a corrosive slime, targeting one creature that it can see within 60 feet of it. The target must make a DC 21 Dexterity saving throw. On a failure, the target takes 55 (10d10) acid damage. Unless the target avoids taking any of this damage, any metal armor worn by the target takes a permanent −1 penalty to the AC it offers, and any metal weapon it is carrying or wearing takes a permanent −1 penalty to damage rolls. The penalty worsens each time a target is subjected to this effect. If the penalty on an object drops to −5, the object is destroyed.

LEGENDARY ACTIONS

The Umi-Bozu can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The Umi-Bozu regains spent legendary actions at the start of its turn.

• Acid Splash. The Umi-Bozu casts acid splash.
• Attack. The Umi-Bozu makes one tentacle smash attack.
• Corrupting Touch (Costs 2 Actions). Melee Weapon Attack: +14 to hit, reach 15 ft., one creature. Hit: 21 (4d6 + 7) poison damage and the target is slimed. Until the slime is scraped off with an action, the target is poisoned, and any creature, other than an ooze, is poisoned while within 10 feet of the target.