The Plague Keeper is a craftable post-Moon Lord broadsword and upgrade to the Bee Keeper and Virulence. When swung, it releases a large cloud of plague dust that goes through tiles and can pierce infinitely, as well as a swarm of over 20 bees. It also releases more bees upon direct contact with enemies. The plague dust deals as much damage as the sword itself, whereas each bee deals 1/3 of the sword's damage.
Its best modifier is Legendary.