Royal Gel

Royal Gel is an accessory obtained from the Treasure Bag dropped by King Slime in Expert Mode. While equipped, most slimes will become friendly, no longer pursuing the player, and will deal no contact damage or fire projectiles, even if the player deals damage to them.

This does not apply to the following slimes:
 * Hoppin' Jacks
 * King Slime and his Spiked Slimes, though the normal Blue Slimes that King Slime spawns remain docile.
 * and her Bouncy Slimes, Crystal Slimes, and Heavenly Slimes.
 * and her Bouncy Slimes, Crystal Slimes, and Heavenly Slimes.

Tips

 * This accessory is particularly valuable during Slime Rain, as it allows the player to kill almost all enemies without worrying about taking damage.
 * This accessory can keep Lava Slimes away while building a bridge for the Wall of Flesh, especially useful since they spread lava on death. In Hardmode, they can prevent Gastropods from shooting the player with lasers, making it much easier to fish or farm enemies in The Hallow at night.

Trivia

 * The Royal Gel's name may be inspired by, a food substance that bee workers feed to bee larvae to change how they grow, specifically so the larvae can become a queen bee.