Multiattack. The cultist makes three attacks, using Elemental Flail or Elemental Claw in any combination.
Elemental Flail. Melee Attack Roll: +7, reach 5 ft. Hit: 25 (6d6 + 4) damage of a type chosen by the cultist: Acid, Cold, Fire, Lightning, or Thunder.
Elemental Claw. Ranged Attack Roll: +7, range 120 ft. Hit: 22 (4d10) damage of a type chosen by the cultist: Acid, Cold, Fire, Lightning, or Thunder. If the target is a Medium or smaller creature, the cultist moves the target up to 10 feet straight toward or away from itself.
Spellcasting. The cultist casts one of the following spells, using Wisdom as the spellcasting ability (spell save DC 15):
At will: Elementalism, Mage HandElemental Absorption (1/Day). Trigger: The cultist takes Acid, Cold, Fire, Lightning, or Thunder damage. Response: The cultist gives itself Resistance to that instance of damage and gains 10 Temporary Hit Points.