Herald of Slaughter

The calm emotions spell instantly fails when cast within 60 feet of the herald. In addition, any creature that starts its turn within 30 feet of the herald must succeed on a DC 16 Wisdom saving throw or grow hostile. On its turn, a hostile creature must move to and make one attack against the nearest creature other than the herald. If no other creature is near enough to move to and attack, the hostile creature stalks off in a random direction, seeking a target for its hostility. At the start of each of the herald’s turn, it chooses whether this aura is active.

The herald’s innate spellcasting ability is Charisma (spell save DC 16). It can innately cast the following spells, requiring no material components:
At will: detect thoughts
3/day: charm person, fear, suggestion
1/day: modify memory, seeming

The herald’s weapon attacks are magical.

The herald can use its action to polymorph into a Small or Medium humanoid it has seen, or back into its true form. Its statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn’t transformed. It reverts to its true form if it dies.

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) slashing damage plus 9 (2d8) necrotic damage.

Ranged Spell Attack: +8 to hit, range 120 ft., one target. Hit: 18 (4d8) fire damage, and the target must succeed on a DC 16 Constitution saving throw or be blinded until the end of its next turn.

Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 4) piercing damage, and the target must succeed on a DC 16 Strength saving throw or be knocked prone.

The herald of slaughter makes three attacks: one with its gore and two with its cleaver. Alternatively, it can use Enkindle Hate twice. If it hits one target with Enkindle Hate twice using this action, the target must succeed on a DC 16 Charisma saving throw or use its reaction to immediately move up to half its speed and make one melee attack against a random target within range.