Cultist
The Cultist is an Act 1 enemy with 48-54 HP. It begins combat with Incultation, which buffs itself with Ritual (gaining Strength each turn), and then repeatedly uses Dark Strike (6-9 damage). The Ritual buff causes its damage to escalate turn by turn — early in the fight Dark Strike is manageable, but by turn 3-4 the Cultist can deal very high damage.
Cultists are deceptively dangerous if ignored. The escalating Strength makes it important to kill them quickly rather than letting them ramp up. They are a primary reason why strong turn-1 damage is valuable in Act 1 deck-building. In multi-enemy encounters featuring a Cultist, prioritizing the Cultist first is usually correct, as its unchecked Strength gain is far more threatening than flat-damage enemies.