Rat King

Rat King is an exotic kinetic sidearm in Destiny 2. It's main perk is Rat Pack, which causes the gun's power to increase when more players with Rat King are nearby. Rat King is acquired by completing the Exotic Quest Rat King's Crew, which is unlocked after completing the Titan World Quest.

Trivia

 * Rat King is named after an aprocyphal phenomenon called a Rat King where several rats have their tails fused together. Mythologically it is treated as a single organism and an omen of bad luck, due to rats association with disease.