Heliana's Guide to Monster Hunting, pg. 509
Cantrip Arcane, Evocation
You momentarily shut down a small part of the nervous system of a creature you can see within range, before overstimulating it and causing crippling pain. The creature must succeed on a Constitution saving throw or take 1d8 psychic damage. If the target fails its saving throw by 5 or more, it has disadvantage on the next attack roll it makes before the end of its next turn as it temporarily loses full control of a part of its body.
This spell’s damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8).