Minecraft wiki entry for Pillager, associated text: If a player kills a pillager captain (a pillager wearing an ominous banner ‌[Java Edition only]/illager banner ‌[Bedrock Edition only] on its head), they receive the Bad Omen status effect. The effect lasts for 100 minutes (5 in-game days) and can be removed by drinking milk. When a player afflicted with Bad Omen enters a village, a raid commences in that village, bringing about waves of illagers that seek and try to eliminate all villagers in the village.