Multiattack

The son of Fenris makes one Bite attack and two Slam attacks, or it makes four Divine Bolt attacks.

Bite

Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 19 (2d10 + 8) piercing damage plus 10 (3d6) necrotic damage or radiant damage (the son's choice). If the target is a Large or smaller creature, it must succeed on a DC 18 Dexterity saving throw or be swallowed by the son of Fenris. A swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the son, and it takes 21 (6d6) acid damage at the start of each of the son's turns. The son can have only one creature swallowed at a time.

Slam

Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 13 (1d10 + 8) bludgeoning damage plus 10 (3d6) necrotic damage or radiant damage (the son's choice).

Divine Bolt

Ranged Spell Attack: +8 to hit, range 60 ft., one target. Hit: 18 (4d6 + 4) necrotic damage or radiant damage (the son's choice).

Snake Breath (Recharge 5-6)

The two snake tongues of the son of Fenris each exhale poison in a 30-foot line that is 5 feet wide, resulting in two lines. Each creature in a line must make a DC 18 Dexterity saving throw, taking 45 (10d8) poison damage on a failed save, or half as much damage on a successful one. If the lines overlap, each creature in the overlapping lines must make one saving throw with disadvantage against only one of the lines rather than one saving throw for each line.