Curse of the Fire Penguin

Drawing upon chaotic necromantic energies tinged with fiery wrath, you curse a single target within 60 feet to transform into a Fire penguin. The target must succeed on a Wisdom saving throw or be transformed against their will. While in penguin form, the cursed creature retains its mental statistics but cannot use any spells, effects, or abilities from its original form. Its physical attributes are replaced with those of a fire penguin: 14 AC , 20 feet movement speed, and immunity to fire damage. Moreover, the cursed target emits a fiery aura, causing 3 (1d6) fire damage to any creature that ends its turn within 5 feet. The transformation also confers a -3 penalty to Charisma-based checks. Every 10 minutes, the target can attempt another Wisdom saving throw. On success, the transformation ends, leaving behind a trail of ember feathers, marking the ground with flames of their passage. Should the transformation last for the entire duration, the target is exhausted upon reverting, gaining one level of exhaustion as a sign of their mystical ordeal.