Nice Work Dawg!
From Halopedia, the Halo wiki
Nice Work Dawg! is an achievement in Halo: The Master Chief Collection. It is unlocked by earning a total of 2,500 Assist medals in multiplayer; this includes both matchmaking and custom games. Spartan Ops missions are considered custom games, as are custom Firefight matches. Assists earned in Firefight matchmaking do not count. The achievement is worth 5 Gamerscore.
- The achievement's name probably comes from a line frequently spoken by Marine NPCs in Halo: Spartan Assault.
- From launch until the April 2022 update, players could not progress this achievement by playing Halo 3 multiplayer matches, as it was the only game in the Collection which did not award the Assist medal. Following the update, assists can now be earned in that game as well.