Curse of Lycanthopy

Until dispelled, this curse will attempt to magically transform the victim of your curse into a medium-sized creature of your choice (chosen at the time of casting) whenever the full moon rises.  If the victim of this curse chooses to resist the change, they can roll a CHA, INT or WIS save (whichever is highest) to turn into an anthropomorphic version of that animal, and they can roll a second CHA, INT or WIS save (whichever is highest) to prevent the change entirely.  Both saves are made at a disadvantage.

The victim of this curse can also attempt to willingly change their form.  Doing so requires passing the same saves as resisting the curse.  Conscious changes are made with advantage on the day of the full moon, and with disadvantage other days.

The victim of this curse can spread it to others by scratching or biting them while in animal or anthropomorphic forms, through sexual transmission, or through childbirth.

The damage that victims take from non-silvered, non-magical weapons depends on their form.  In their normal, unchanged form, they are as susceptible to this kind of damage as anyone else.  In their anthropomorphic form, victims take half damage.  In animal form, victims take none of this kind of damage. 

However, in any form, ingesting, injecting or implanting concentrated silver or wolfsbane is poisonous.  Both silver and wolfsbane provoke allergic reactions when victims of lycanthropy touch them.  Placing wolfsbane near the edge of a doorway forces victims of the curse to pass a CHA save to willingly pass through the doorway.  If they are forced through a wolfsbane-protected doorway despite failing that save, they will become poisoned.

Animal Form

In animal form, the victim's game statistics are replaced by the statistics of the chosen creature.  They assume the hit points and Hit Dice of the new form. When they revert to their normal form, they return to the number of hit points they had before they transformed. If they revert as a result of dropping to 0 hit points, any excess damage is neutralized.  They can't use any special senses they have (for example, darkvision) unless their new form also has that sense. They can only speak if the creature can normally speak.

The GM determines whether it is practical for the new form to wear a piece of equipment, based on the creature's shape and size. Their equipment doesn't change shape or size to match the new form, and any equipment that the new form can't wear must fall to the ground.

Anthropomorphic Form

In anthropomorphic form, the victim's CON, DEX and STR abilities are increased by 1, while their CHA, INT and WIS abilities are lowered by 1.  This also grants them a number of temporary hit points equal to (New CON x Level) + 2.  When they revert to their normal form, they return to the number of hit points they had before they transformed. If they revert as a result of dropping to 0 hit points, any excess damage is neutralized. 

In this form, the victim's retain the benefit of any features from their class, race, or other source and can use them, provided that their new form is physically capable of doing so.   In addition, they gain any special abilities possessed by the animal, but at half the animal's range or potency.  Any of the animal's abilities that cannot be scaled in this way will be dropped.

In anthropomorphic form, the victim's equipment is worn by their new form, and functions as normal.

Curing Lycanthropy

Those who are born with lycanthropy can only be cured with a Wish spell, or equivalent.

Those who have contracted lycanthropy from others can be cured by a successful Remove Curse spell.  If the Remove Curse spell fails, the victim must roll higher than a 2 on a d20 roll to avoid permanently transforming into their anthropomorphic form.  If they fail that roll, they will no longer be infectious, although they will pass on some animal traits to their offspring.