Gamma Heart

The Gamma Heart is a post-Moon Lord summon weapon that drops from Nuclear Terrors. It summons a Gamma Hydra that is attached to the player, with each resummon consuming one additional minion slot for an extra head. The heads fire Gamma Bullets at nearby enemies which inflicts the Sulphuric Poisoning debuff. If the player possesses seven or more heads, a Gamma Canister has a chance to appear. If a head comes into contact with a Gamma Canister, all existing Gamma Heads fire a Gamma Deathray in the cursor's direction that deals 120% of the weapon's damage and inflicts Electrified on enemy hits.

Trivia

 * Like the Nuclear Terror, The Gamma Hydra's design was inspired, albeit more directly, by the Horror character from the game Nuclear Throne.
 * In the game, Horror can shoot out a green beam using radiation collected from canisters, in a similar fashion to how the Gamma Heart works.