Disruptive Wisp

You call upon a spirit of mischief to disrupt an enemy. The spirit is translucent and resembles the form of your choice.

choose a creature you can see. The spirit manifests in the square of your chosen creature and follows them. Until the spell ends the target subtracts a 1d4 on all attack rolls, ability checks, and saving throws they roll. 

As a reaction, you can end the spell early and apply one of the following effects to the target.
The target subtracts 2 to a rolled saving throw.
When the target reaches 5 hitpoints the caster can use their reaction to cause the target to become unconscious. The caster should be prompted by the DM when the creature reaches this threshold 
The target subtracts 2 from their AC. This can cause an attack that originally missed to hit.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, Increase the values of the reaction subtraction to saving throws and AC by 2 for each slot level above 1st. Also, increase the hitpoint threshold for unconsciousness by 5 for each slot level above 1st.