Slowness

Slowness decreases walking speed.

Effect
Slowness decreases walking speed by 15% × level and contracts the player's field of view accordingly. Negative levels of Slowness increase walking speed. However, jump-sprinting is barely affected.

Unaffected mobs
Boss mobs are immune to the Slowness effect. While not immune, flying mobs are unaffected by the Slowness effect. Shulkers are also unaffected by, though not immune to, Slowness.