You are cursed with arouranthropy, the curse of the wererat, granting you the following features:

BLOOD DRINKER

Whenever you finish a long rest without consuming at least 1 pint of blood, you become exhausted, which can't be removed in any way except by consuming 1 pint of blood.

SHAPECHANGE

You can take the Magic action to transform into your Animal Form, Hybrid Form, or back into your humanoid form.

ANIMAL FORM

You transform into a rat. While transformed by this feature, you are impaired.

HYBRID FORM

You transform into a wererat. While transformed by this feature, you are impaired, and you gain the following features:

ABILITY SCORE IMPROVEMENT

Your Dexterity scores becomes 15, provided it isn't already 15 or higher.

CURSED BLOOD

When you take the Attack action while unarmed and hit a humanoid creature, the target must make a Constitution saving throw against your Constitution DC. On a failed save, the target becomes becomes cursed with arouranthropy (wererat). On a successful save, the target becomes immune to the effects of this feature for 24 hours.

DARKVISION

You have darkvision (60 feet).

KEEN SMELL

You have proficiency in the Perception skill, and advantage on Wisdom (Perception) checks that rely on smell.

NATURAL WEAPONS

While unarmed, you can take the Attack action with your bite (1d4 piercing).

PHYSICAL IMMUNITY

You have immunity to bludgeoning, piercing, and slashing damage from non-silver weapons.

STEALTHY

You have mastery in the Stealth skill.