Blacephalon (5e Creature)
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Medium aberration, neutral
Beast Boost. When Blacephalon reduces a hostile creature to 0 hit points, the DC for its Mind Blown ability and it Dexterity saving throw increase by 3. This bonus is cumulative, but resets when Blacephalon takes a long rest.
Multiattack. Blacephalon makes two shadow ball attacks.
Shadow Ball. Ranged Spell Attack: +7 to hit, range 20/60 ft., one target. Hit: 25 (6d6 + 4) psychic damage.
Mind Blown (Recharge 6). Blacephalon causes its own head to explode, and it and every creature within 30 feet of it must make a DC 15 Dexterity saving throw, taking 70 (20d6) fire damage on a failed save, or half as much damage on a successful one. Blacephalon is then blinded and deafened until the start of its next turn, when its head grows back.
Blacephalon is exceedingly fragile, but its deadly ability to explode makes it almost impossible to fight without heavy casualties. It sways in a rhythmic, dancing motion to lull opponents into a trance before it begins its flurry of attacks.