A Chaos Champion trying to become a daemon prince, and our duty would be to stop his/her ascendance?

I smell Tartarus MK2. (Btw Sindri fight in the book was much cooler than in the game)

You mean the... Dawn of War book?

Aye. It was pure crap lore-wise.... But story and action wise it was way better than the games.... At least it was deeper.

Considering the game used the in-game engine for the fight.

Well.. it was made by Multilaser Goto.

I havent read the books yet are they that bad. Also we could be on a mission assist by Grey knights Space marines maybe even spacewolfs that are Trying to push xeno and heratic forces off the world while a chaos champion of slannesh Plans to sacrfice some eldar souls stones to asscend. Its the job of the space marines to take down the Chaos space marine before he can assend and the sisters to help defend or fight off xeno forces.

While I would love the prospect of working with the SM normally, I think here it'd be better if it was just Sororitas and other assorted Ecclesiarchy/Imperium stuff. SM have this tendency of stealing spotlight.

Did you even read the Sindri Myr fight? Where he ascended to Daemon prince and Angelos and Macha were jumping from levitating rock to rock, slaying heretics down until eventually reach the semi-ascended sorcerer?

Yeah, it's time for the Sororitas to take spotlight