The Colony Leader Add-on for Halo Wars 2 has 3 achievements worth 30 gamerscore.
Win 3 matches as Colony (Multiplayer, Skirmish or Blitz)
Attach 50 skitterers to units (Multiplayer, Skirmish or Blitz)
Use the Hunter Captain's Taunt ability 50 times (Multiplayer, Skirmish or Blitz)