Ammit, The Devourer of Souls

Celestial Prison. Ammit, the Devourer can choose to Swallow one willing target if it is a Medium or smaller creature. This creature is blinded and restrained and is magically  sustained indefinitely until it is released.

 Spellcasting. Ammit, Devourer of Souls is a 4th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 22, +14 to hit with spell attacks). Ammit,  Devourer of Souls has following Cleric spells prepared:

Cantrips (at will): Toll the Dead, Spare the Dying

1st level (3 slots): Detect Evil and Good, Protection from Good and Evil

2nd level (2 slots): Hold Person, Zone of Truth

3rd level (2 slots): Tongues, Dispel Magic

4th level (1 slot): Banishment

Multi Attack. Ammit, Devourer of Souls can use its Righteous Breath. It then makes two attacks: one with its bite and one with its Guiding Bolt or Swallow.

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 19 (2d10 + 8) piercing damage plus 9 (2d8) radiant damage. If the target is a Medium or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and Ammit, the Devourer can't bite another target.

Guiding Bolt. Ranged Spell Attack:  +14 to hit, reach 120 ft., one target. Hit: 35 (7d6) radiant damage and before the end of your next turn, the next attack roll made on it has advantage.

Swallow. Ammit, the Devourer makes one bite attack against a Medium or smaller target it is grappling. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is blinded and restrained, it has total cover against attacks and other effects outside Ammit, the Devourer, and if the swallowed target is an Undead or Fiend it takes 20 (3d12) radiant damage at the start of each of Ammit, the Devourer's turns. Ammit, the Devourer can have only one target swallowed at a time. If Ammit, the Devourer dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone, unless it is an Undead or a Fiend, which die along with Ammit, the Devourer.

Righteous Breath (Recharge 5–6). Ammit, Devourer of Souls exhales in a 60-foot cone. Each creature of her choice in that area must make a DC 22 Wisdom saving throw, becoming frightened on a failed save. Any Undead or Fiends that fail the throw are Stunned.