Warden's Leash

This spell can only be cast upon a willing target. The target of this spell is bound to an oath to the caster. Should they fail to complete their end of the bargain in the agreed-upon time, the spell takes effect.

The effects of the spell taking effect can vary from caster to caster, but all represent dire consequences for failing to complete the bargain. Alternatively, you can roll a D8 to determine the effect. 

1 - The target will be banished to the ethereal plane forever, unable to interact with anyone or anything on the material plane
2 - Food will no longer provide nourishment to the target, nor will it abate their hunger. Creatures that normally do not require food will develop the hunger and need for it. 
3 - Water will become fatally poisonous to the target, but they will thirst like normal. Creatures that normally do not require water will develop the thirst and need for it. 
4 - Every time the target takes a long rest, the time required to recover energy and abilities increases by one hour. Creatures that normally do not require rest will find that now do.
5 - Every day the target's constitution decreases by 1
6 - The target becomes markedly weaker in all aspects, with their modifiers being permanently set to -4
7 - If the target stops moving, even for a moment, their speed will permanently reduce by 1 foot. This does not reset. If the target's speed ever reaches 0, they will turn to stone and be frozen in place forever. 
8 - The target dies, and will be unable to be resurrected. 

Upon successful casting of this spell, the caster speaks out loud the required task, the penalty, and the time to complete it. At that point, the target's clock begins to tick. If the time expires, the spell takes effect. This spell can only be dispelled by the caster, or via a Wish spell, or similar magic. Additionally, the consequences for failing to complete the task on time can only be undone by a Wish spell or similar magic.