Disrupt Bloodstream

You cause the blood in a foe you can see to boil or chill to unsettle them. One creature of your choice that you can see within range must make Constitution saving throw. Whenever a target that fails this saving throw makes another saving throw, attack roll or ability check the target must roll a d4 and subtract the number rolled from the result. 

At Higher Levels. When you cast this spell using a spell slot of 1st level or higher, you can target one additional creature equal to the spell level.