The Rise of the Horde Title update for Gears of War 4 has 20 achievements worth 500 gamerscore.
Upgrade 5 Skill Cards to Level 6
Craft a Craft Only card
Upgrade a Skill Card to Level 6
Destroy a card
Complete 50 consecutive waves of Horde in a squad on any Post Launch map
Complete 50 consecutive waves of Horde in a squad on five Post Launch maps
Complete 50 consecutive waves of Horde as Sniper on Inconceivable in a squad (any map)
Complete 50 consecutive waves of Horde as Soldier on Inconceivable in a squad (any map)
Complete 50 consecutive waves of Horde as Scout on Inconceivable in a squad (any map)
Complete 50 consecutive waves of Horde as Heavy on Inconceivable in a squad (any map)
Complete 50 consecutive waves of Horde as Engineer on Inconceivable in a squad (any map)
Complete 50 consecutive waves of Horde as Soldier on Ironman (Hardcore or higher) in a squad
Complete 50 consecutive waves of Horde as Sniper on Ironman (Hardcore or higher) in a squad
Complete 50 consecutive waves of Horde as Scout on Ironman (Hardcore or higher) in a squad
Complete 50 consecutive waves of Horde as Heavy on Ironman (Hardcore or higher) in a squad
Complete 50 consecutive waves of Horde as Engineer on Ironman (Hardcore or higher) in a squad
Upgrade all Skills Cards for one Horde class to Level 6
Complete all Campaign Acts on Inconceivable difficulty
Complete all Campaign Acts on Ironman in Co-op on Hardcore or higher difficulty
Complete all Campaign Acts on Ironman (Hardcore, Insane, or Inconceivable difficulty)