Merregon

Medium Fiend (devil), Lawful Evil

MPMM

AC 16 (natural armor)

HP 45 (6d8 + 18)

Speed 30 ft.

STR

18 (+4)

Save +4

DEX

14 (+2)

Save +2

CON

17 (+3)

Save +3

INT

6 (-2)

Save -2

WIS

12 (+1)

Save +1

CHA

8 (-1)

Save -1

Resistances Cold; Bludgeoning, Piercing, Slashing (from nonmagical attacks that aren't silvered)

Immunities Fire; Poison

Condition Immunities Frightened, Poisoned

Senses darkvision 60 ft., Passive Perception 11

Languages understands Infernal but can't speak, telepathy 120 ft.

CR 4

Devil's Sight. Magical darkness doesn't impede the merregon's darkvision.

Magic Resistance. The merregon has advantage on saving throws against spells and other magical effects.

Multiattack. The merregon makes three Halberd attacks.

Halberd. 6 to hit, reach 10 ft., one target. Hit: 9 (1d10 + 4) slashing damage.

Heavy Crossbow. 4 to hit, range 100/400 ft., one target. Hit: 7 (1d10 + 2) piercing damage.

Loyal Bodyguard. When another Fiend within 5 feet of the merregon is hit by an attack roll, the merregon causes itself to be hit instead.