Hold Breath. Krull can hold his breath for 1 hour.

Inescapable Destruction. Necrotic damage dealt by Krull's spells ignores resistance to necrotic damage.

Spellcasting. Krull is a 14th-level spellcaster. His spellcasting ability is Wisdom (spell save DC 16, +8 to hit with spell attacks). He has the following cleric spells prepared:

Cantrips (at will): chill touch, mending, resistance, sacred flame, spare the dying, thaumaturgy

1st level (4 slots): cure wounds, detect evil and good, false life, inflict wounds, ray of sickness

2nd level (3 slots): blindness/deafness, gentle repose, hold person, ray of enfeeblement, spiritual weapon

3rd level (3 slots): animate dead, magic circle, speak with dead, spirit guardians, vampiric touch

4th level (3 slots): banishment, blight, death ward, divination, locate creature

5th level (2 slots): antilife shell, cloudkill, contagion, greater restoration

6th level (1 slot): create undead, true seeing

7th level (1 slot): divine word, regenerate

Claws. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit:7 (1d4 + 5) piercing damage.

+1 Maul. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit:13 (2d6 + 6) bludgeoning damage plus 9 (2d8) necrotic damage.

Shell Defense. Krull withdraws into his shell. Until he emerges as a bonus action, he has a +4 bonus to AC and has advantage on Strength and Constitution saving throws. While in his shell, Krull is prone, his speed is 0 and can't increase, he has disadvantage on Dexterity saving throws, he can't take reactions, and the only action he can take is to emerge from his shell.