Tutorials/Raid farming

Raid farming is a means to obtain items dropped by raid mobs (pillagers, vindicators, witches, evokers, and ravagers), as well as special items dropped by these mobs during raids: emeralds, enchanted books, iron tools, and iron armor (of which half has enchantments).

Mechanics
Broadly the components of a raid farm are:
 * a village (1 bed and 1 villager are sufficient)
 * a surface on which the raid is forced to spawn (the ground, or an isolated surface above)
 * a way to funnel or guide the raid mobs
 * a killing area; that is, mob grinder to kill the mobs, or a holding area for the player to kill them and earn experience as well as loot.
 * a way to get Bad Omen again, to that the next raid can start:
 * either a pillager outpost converted to a pillager trap to allow the player to kill Raid captain that spawn in the outpost,
 * or a way to force the Raid captains in the raid out of the raid context, so that they give Bad Omen when killed.