Bestow Trigger Curse

When you cast this spell, you may choose any of your spells that you in your repertoire at the current time and then cast them simultaneously within the casting of the trigger curse, disregarding the verbal, and semantic casting components, but not the casting time. You touch a creature and if hostile making a spell touch attack. On a hit, that creature must succeed on a Wisdom saving throw or become cursed until the curse is dispelled or until the curse is triggered. You may only have one curse of this type active at any one time.

Whatever spell is cast through this curse must have its casting time or ritual if required, completed before the curse is finished and acts as the casting time for the curse. After the curse is finished and cast the caster must state to the DM what is the trigger for the curse. Triggers can be a set amount of time, a certain moon phase, a drop in health points, or any other unique and specific event, this is open-ended for a caster to determine the trigger. The curse persists as long as the trigger never happens or the curse is not dispelled. Instead of selecting a spell effect based on a trigger you may also try to create a harmful effect similar as listed in the Bestow Curse spell. 

An example of this spell might be cursing a target next time the are knocked prone that they suffer the effect of a fireball spell.

A Remove Curse spell must be cast at the same spell level to dispel this curse. A greater restoration cannot dispel the curse nor remove any particular parts of the spell. A wish spell can remove or alter this curse.