An Evoker is a hostile, humanoid mob found in the Overworld. They are one of five types of Illagers ("ill-willing villagers"), the other four being the Illusioner, the Vindicator, the Pillager, and the Ravager.
An Evoker's noises are sinister, saying "Hrrrm," "Harrurm," and "Hun." They also say "Wololo" sound when performing a spell.
Overview
Evokers are considered illagers, which means that they are hostile outcasts from villages. They look similar to villagers, except their skin is gray in color instead of brown. Evokers are found inside particular rooms of the Woodland Mansion, one at a time. They may be accompanied by 1–3 Vindicators.
Behavior
Evokers are hostile towards Players, Villagers, and Iron Golems within a 16-block range. One of their attacks summons tiny hostile pixies called Vexes. Their second attack spell summons several evoke several clamp-traps from the ground in either a ring or a long line, depending on their target's distance.
These clamp-traps, known as Evocation Fangs, are evoked in either a 20-m line for distant targets or an inner ring of 5 fangs with an outer ring of 8. They deal 
damage upon snapping shut.
Evokers flee when attacked and not casting a spell.
Drops
Evokers always drop a single Totem of Undying when killed by a player. They sometimes also drop an Emerald. Swords with the Looting Enchantment only affect their emerald drops.
History
These mobs were added to Minecraft in 1.11 - The Exploration Update.
Trivia
- When not in combat, evokers change any blue sheep they find into red sheep, uttering "Wololo."
- This is a reference to the video game Age of Empires where the priest unit would convert enemy units to their own side while uttering "wololo". [1]
- While summoning a vex, an evoker emits gray swirls above its head, as if under the effects of a Potion.
- The evoker was originally going to wear a white hood similar to that of the illusioner. This can be seen in Meet the Evoker. (This hat model was also going to be used for witches and several villager types).
- Evokers are still present in peaceful mode, but they flee from players and don't attack them.
