Magic Leeching.  If the leech touches the skin of a spellcaster while not incapacitated, it starts feeding off of the character's spell slots. The character must then make a DC 15 Charisma saving throw. On a failure, the character loses one spell slot, starting with the highest spell slot level available, as if the character had cast a spell of that level. If the character has no spell slot left, they can’t cast cantrip until they finish a long rest. The character can’t regain that spell slot as long as the leech is feeding on them.

 

If the character rolls a 1 on this saving throw, they lose that spell slot permanently, even if the leech stops feeding on them. This effect is considered a curse and can be undone by any effect that removes a curse, such as a greater restoration or remove curse spell.

 

The leech stops feeding off of the character if a character within 5 feet of it uses their action to remove it from the spellcaster’s skin or if it is rendered incapacitated.