Terraprisma

The Terraprisma is a Hardmode summon weapon dropped by the Empress of Light boss. The weapon will only drop if 100% of the damage dealt to the Empress occurs during the daytime, when she is enraged and all attacks are instant-kill to the player (Like Skeletron, Skeletron Prime, and Dungeon Guardian).

When used by a player, it creates a detached copy of itself and autonomously attacks by swinging and stabbing at nearby enemies. Each instance counts towards the standard minion cap.

Its best modifier is Ruthless. The Mythical modifier provides the widest array of stat bonuses, but these primarily affect the initial summon rather than the resulting minion. Additionally, minions cannot deal critical hits. The only lasting advantage a Mythical Terraprisma has over a Ruthless one is knockback.

Trivia

 * Although its sprite appears to be a Sword, it is actually a Summoning Weapon. This is similar to the Sky Fracture, which looks like a sword, but is actually a Magic weapon.
 * It will only be dropped by the Empress of Light if she is entirely damaged and killed during the day, when her attacks will do a significantly increased amount of damage. If any damage is done to her at night, the Terraprisma will not drop.
 * Despite the weapon's tooltip, the summoned minions look neither like the Enchanted Sword item or the Enchanted Sword enemy.
 * The Terraprisma has the highest base damage of all minion summon weapons, despite being a drop from the Empress of Light, a post-Plantera boss, and having a rarity of.
 * The Terraprisma is the only summon weapon, aside from whips and the Tavernkeep's Sentries that does not have the word staff in it's name.