Fifth Floor: Tools, Guns, Super Weapons
From Halopedia, the Halo wiki
Fifth Floor: Tools, Guns, Super Weapons is an achievement in Halo Wars 2, awarded for completing the level The Foundry on any difficulty.[1]
Trivia
The title of this achievement is a reference to the The Library's final section, "Fourth Floor: Tools, Guns, Keys To Super Weapons".
Sources