The Ark of the Elements and its homing projectiles.
The Ark of the Elements is a craftable post-Moon Lord broadsword that autoswings. It is the second-to-last upgrade to the Ark of the Ancients. It fires an enemy-piercing tile-ignoring beam sword of one of four colors when swung. In addition, it rains down three homing projectiles to damage enemies. The sword itself, as well as its blue and orange beams, inflict the Elemental Mix debuffs. The pink and green beams will only inflict Holy Flames.
The Ark of the Elements also has a rare item variant called the Swordsplosion that drops from Bumblebirb.
Its best modifier is Legendary.