Complete the following achievements to unlock Microsoft Gamerscore points.

Chaos Lord (70 points) : Play 20 Ranked games using Chaos.
Blood God (25 points) : Win a Ranked game using only Khorne-themed units.
Plague Father (25 points) : Win a Ranked game using only Nurgle-themed units.
Bringer of Change (25 points) : Win a Ranked game using only Tzeentch-themed units.
Chaos Undivided (25 points) : Win a Ranked Team Battle with each Chaos hero on
the team in Chaos Rising.
King Of The Hill (50 points) : Win 10 online Free for All matches in Chaos Rising.
Manipulator (25 points) : Score 500,000 in The Last Stand with the Hive Tyrant
or Sorcerer in Chaos Rising.
Overlord (60 points) : Reach level 20 in The Last Stand with the Hive Tyrant
or Sorcerer in Chaos Rising.
Usurper (60 points) : Beat wave 20 in The Last Stand with the Hive Tyrant
or Sorcerer in Chaos Rising.
The Enemy Exposed (50 points) : Defeat the true enemy attacking Angel Forge.
Enemy of Chaos (70 points) : Complete campaign on Recruit Difficulty or harder.
Bane of Chaos (70 points) : Complete campaign on Captain Difficult or harder.
End of Chaos (70 points) : Complete campaign on Primarch Difficulty.
Common Foe (25 points) : Complete 1 Chaos Rising mission in Co-Op.
Bad Example (25 points) : Get any squad to maximum Corruption. Not available to guests.
Relentless (25 points) : Reach level 30 with any campaign squad. Not available to guests.
Purist (50 points) : Complete a mission on the Space Hulk with 4 Terminators.
Domination (25 points) : Hold 5+ victory points at once in an online Free for All.


Source: http://www.cheatbook.de/files/warhammer40000dawnofwar2chaosrising.htm