Minecraft wiki entry for Combat, associated text: Vexes are very small creatures about the size of a baby zombie, can only be summoned by Evokers. They float around, passing through blocks and deal damage with iron swords. They do high damage (5.5 × 2.75 on easy, 9 on normal and 13.5 × 6.75 on hard) and have 14 × 7. A player with good gear will be able to kill it in one or two hits. Prioritize killing them over vindicators when the player can see them in range of the sword, as they move fast and can get behind the player.