Curse of the Owlbear

Due to exposure to the Curse by infection or by birth, you gain the ability to transform into a lesser version of an owlbear.

Transforming takes a full round action to perform, but if you have not transformed before being knocked unconscious you may transform instead of rolling a death saving throw. Doing so automatically stabilizes you, but once your transformation ends you will still remain unconscious. 

You can transform once per long rest, and your character health, Strength, Dexterity, and Constitution get replaced by your transformation. You still retain your skills, saving throws, Intelligence, Wisdom, Charisma and class abilities, but cannot cast spells or maintain concentration while in your form. Your transformation lasts for 60 minutes. During transformation all magical equipment is morphed into your form and not damaged, but any mundane equipment is destroyed or dropped during the transformation.

If your transformation form drops to 0 hit points, you are automatically transformed back into your original form and any additional damage that was taken during the attack will be carried over to your base form. For example, if you in owlbear form take 10 points of damage while having 7 hitpoints, you will transform back into your base form and take the remaining 3 damage to your original hitpoint total. If dropped past 0 hit points and your transformation was activated due to being knocked unconscious, you will transform back dying, and have one failed death saving throw.

The details of your transformation are listed below, and the form gains additional abilities once you level up.

Form of the Owlbear

Medium Beast

Armor Class 14 + PB (natural armor)

Hit Points 5 + five times your Character level

Speed 30 ft.

Saving Throws Same as Base form

Senses Darkvision 60 ft., passive Perception: same as base form

Keen Sight and Smell. The owlbear has advantage on active Wisdom (Perception) checks that rely on sight or smell.

Actions

Bite. Melee Weapon Attack: +4 plus PB to hit, reach 5 ft., one target. Hit: 1d8+4 plus PB piercing damage.

Claw. Melee Weapon Attack: +4 plus PB to hit, Reach 5 ft, one target. Hit: 1d6+4 plus PB piercing damage. 

At Level 3, your transformation's speed increases to 40 ft.

At level 5, your Owlbear transformation gains Multiattack, and your attacks count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage while in Owlbear form.

Multiattack. The owlbear makes two attacks: one with its beak and one with its claws.

At Level 7, your transformation size increases to Large, and your transformation's strength increases to 20. This changes your attack and damage rolls from +4 to +5.

At Level 11, your multiattack becomes stronger. During the attack action you attack three times, twice with your claws and once with your bite.