The Score Attack Title update for Halo 5: Guardians has 5 achievements worth 125 gamerscore.
Complete a mission in Score Attack with at least 10,000 points.
Reach 50,000 points in Score Attack with a Skull multiplier of x2 or higher.
Complete a mission in Score Attack co-op, with all participants scoring at least 200,000 points.
Beat the par time of a mission in Score Attack.
Complete a mission in Score Attack with at least 500,000 points.