Minecraft wiki entry for Development_versions, associated text: Players can now trigger a raid when entering a village with the Bad Omen status effect.
Players receive the Bad Omen status effect when killing an illager captain.
Raid states are saved and loaded between sessions.
Ravagers are sometimes ridden by a pillager or vindicator when spawning in a raid.
Raids now use the "dweller component" to track raiders, even when they are unloaded.
Pillagers, vindicators, witches, and ravagers spawned from a raid move toward their village dictated from the dweller component.