Warden (achievement)

From Halopedia, the Halo wiki

Warden is an achievement in Halo: The Master Chief Collection. It is unlocked by stopping the Killing Spree of another player in Halo 2 classic or Halo 2: Anniversary multiplayer. The achievement is worth 10 Gamerscore and can be unlocked in both matchmaking and custom games. It also unlocks the Silver Forge Nameplate.