Bone Swarm
Large Undead (Swarm), chaotic evil
Armor Class 17 (natural armor)
Hit Points 198 (36d10)
Speed fly +60, walk +20
Challenge 10
Saving Throws cha +9, dex +8, wis +6
Skills stealth +8, acrobatics +8, perception +6
Damage Vulnerabilities bludgeoning
Damage Resistances piercing and slashing from nonmagical attacks
Damage Immunities poison
Condition Immunities charmed, exhaustion, frightened, paralyzed, poisoned, prone, restrained, stunned
Senses darkvision 60 ft., passive Perception 16
Languages Common, Void Speech
Special Abilities
Strength of Bone. A bone swarm can choose to deal bludgeoning, piercing, or slashing damage, and adds 1.5x its Strength bonus on swarm damage rolls as bits and pieces of broken skeletons claw, bite, stab, and slam at the victim.
Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a human skull. The swarm can't regain hit points or gain temporary hit points.
Actions
Multiattack. The bone swarm can attack every hostile creature in its space with swirling bones.
Swirling Bones. Melee Weapon Attack: +10 to hit, reach 0 ft., one creature in the swarm's space. Hit: 31 (5d8 + 9) bludgeoning, piercing, or slashing damage (includes Strength of Bone special ability).
Death's Embrace (Recharge 5-6). Melee Weapon Attack: +10 to hit, reach 0 ft., one creature in the swarm's space. Hit: the target is grappled (escape DC 16) and enveloped within the swarm's bones. The swarm can force the creature to move at its normal speed wherever the bone swarm wishes. Any non-area attack against the bone swarm has a 50 percent chance of hitting a creature grappled in Death's Embrace instead.
Source: Tome of Beasts · OGL/Open