Janos's Tiny Improvement

With the confidence of a master transmuter, you make a tiny anatomical improvement to a creature's body. The target's opinion of your improvement is, of course, irrelevant.

Choose one creature you can see within range and one of the following effects. The target must succeed on a Constitution saving throw or suffer the chosen effect for the spell's duration.

Tongue Knot. The target's tongue and vocal tract are subtly rearranged into a harmless knot, preventing the production of vocal sounds. The target can't speak, produce Verbal components, or make any vocal noise.

Stone Joints. The target's joints partially calcify, becoming stiff and resistant to sudden movement. The target's Speed is halved, it can't take Reactions, and it has a -2 penalty to AC.

Asymmetric Limbs. The target's limbs become subtly asymmetrical, disrupting its coordination. The target has Disadvantage on attack rolls.

Using a Higher-Level Spell Slot. If you cast this spell using a 4th-level spell slot, you can maintain Concentration on it for up to 10 minutes. If you cast it using a spell slot of 5th level or higher, you can maintain Concentration on it for up to 8 hours. If you cast it using a 9th-level spell slot, the spell doesn't require Concentration, and it lasts until dispelled.