Wither Armor is a status effect that the Wither boss can have. It automatically starts when the boss is down to half health. Wither Armor makes the Wither impervious to projectiles. However, while Wither Armor is on, the Wither will sink down in the air, allowing the player to hit it with melee weapons. Wither Armor is a shimmering effect similar to that of a charged Creeper. It has no offensive benefits to the Wither, thankfully.