Warden Achievement in Halo: The Master Chief Collection

In order to unlock this achievement, you must obtain a Killjoy medal in any Halo 2: Anniversary Multiplayer map. This medal is awarded to players for killing an enemy player who is on a Killing Spree of five kills or higher. As such, this will most likely come naturally as you play various different FFA and Team-based game types. Please take note that this cannot be boosted in a Custom Game.