Yeenoghu cultist (Berserker)

Dark Devotion. The berserker of Yeenoghu has advantage on saving throws against being charmed or frightened. 

Reckless. At the start of its turn, the berserker can gain advantage on all melee weapon attack rolls during that turn, but attack rolls against it have advantage until the start of its next turn.

Innate Spellcasting. follower of Yeenoghu's innate spellcasting modifier is Wisdom (spell save DC 12). The follower of Yeenoghu can innately cast the following spells, requiring no spell components: 

1/day: Tasha's hideous laughter, crown of madness, fear

Rampage. When this creature reduces a creature to 0 hit points with a melee attack on its turn, it can take a bonus action to move up to half its speed and make its Gnashing Jaws attack once.

Aura of Bloodthirst. If this creature isn’t incapacitated, any creature with the Rampage trait can make its Gnashing Jaws attack as a bonus action while within 10 feet of this creature.

Multiattack. The berserker makes two melee attacks.

Gnashing Jaws.  Melee Weapon Attack:  +7 to hit, reach 5ft., one creature. Hit:  7 (1d4 + 5)  piercing damage.

Greataxe. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (1d12 + 5) slashing damage.