Huge beast, unaligned
Armor Class 18
Hit Points 225 (18d12 + 108)
Speed 30 ft., burrow 10 ft., swim 30 ft.
Damage Resistances bludgeoning, piercing, and slashing
Damage Immunities poison
Condition Immunities poisoned
Senses darkvision 90 ft., tremorsense 30 ft., passive Perception 11
Challenge 14 (11,500 XP)
Charge. If the bull cantankeri moves at least 20 feet straight toward a target and then hits it with a slam attack on the same turn, the target takes an extra 22 (5d8) bludgeoning damage. If the target is Large or smaller, it must succeed on a DC 19 Strength saving throw or be knocked 5 feet back for each size category below Huge.
Relentless (Recharges after a Short or Long Rest). If the bull cantankeri takes 30 damage or less that would reduce it to 0 hit points, it is reduced to 1 hit point instead.
Siege Monster. The bull cantankeri deals double damage to objects and structures.
Star Swimmer. While on the astral plane, the bull cantankeri can use swimming movement as if it were flying.
Multiattack. The bull cantankeri makes one slam attack and one bite attack.
Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 19 (5d6 + 2) piercing damage.
Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 33 (5d8 + 11) bludgeoning damage.
The cantankeri are lumbering, irritable, half-fossilized isopods capable of battering through a ship’s hull. Sometimes, miners digging into chunks of rock drifting through the astral plane find sleeping cantankeri instead of metal or precious stones. Stunted, half-blinded and irritable from their long sleep, the cantankeri are not pleased to be disturbed.
The bull is a king of its kind. An isopod with the dimensions of an elephant, sheathed in layer upon layer of semi-calcified armour plates, all wrapped around the temperament of an embittered badger. Bull cantankeri are aggressive, and once roused, will bash themselves against a foe until either it or they are dead. During the battle it's not unusual for fragments or belongings of their victims to become wedged in the bull's carapace.
Their world died long ago. When their world was dying, they didn't fix it, or try to leave. They just burrowed into its crust, and slept until the end. It crumbled around them, and they woke amongst its fragments. They gather in old places to grumble and grunt at each other, like they're planning something. Or telling stories.
Their outer layers are encrusted with stone from their long slumber in the crust of their dying world. In places, it is traced with shimmering veins of mineral. Sometimes, clusters of jasper, tourmaline, or agate can be found embedded in the calcified plates of their carapace.