Medium Elemental, neutral evil
Armor Class 13
Hit Points 52 (8d8+16)
Speed fly +60, walk +0
Challenge 2
Skills perception +0
Damage Resistances lightning; nonmagic B/P/S attacks
Damage Immunities poison
Condition Immunities exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious
Senses darkvision 60', passive Perception 10
Languages Auran
Air Form. Can enter a hostile creature's space and stop there. Can move through space as narrow as 1ft. wide with o squeezing.
Asphyxiate. If a creature that breathes air starts its turn in miasma's space it must make DC 12 Con save or begin suffocating as its lungs fill with the poisonous air emitted by the miasma. Suffocation lasts until creature ends its turn in a space not occupied by baleful miasma or the baleful miasma dies. When the suffocation ends the creature is poisoned until the end of its next turn.
Elemental Nature. Doesn't require air food drink or sleep.
Multiattack. Two Slam attacks.
Slam. Melee Weapon Attack: +5 to hit, 5 ft., one target, 6 (1d6+3) bludgeoning damage + 3 (1d6) poison.
Swift Advance. If a creature in same space as miasma moves miasma can move up to its speed with the creature. This move doesn't provoke opportunity attacks but miasma must move in same spaces creature moved ending in creature's space or space nearest to it.
Source: Tome of Beasts 3 · OGL/Open