First post!!!
Anways,

I know that the main SM chapter will be the Black Templars, but will there be instances when other chapters come in to help? Like perhaps other IF 2nd founding chapters like the Imperial Fists or Crimson Fists?

I would put money on the Blood Ravens from the DoW series making an appearance and possibly the Ultra Smurfs, I would doubt other chapters will show up but you never know. It would be nice to have more than just the BT's but I doubt they will ever be playable and for lore reasons I suspect there wnt be any more than one or two other Chapters seen. Possibly Grey Knights but given BT's maybe not.

Welcome btw.

I really want to see some Grey Knights.

Remember, the Sargos sector is kind of near the Eye of Terror. So theres lots of potential for all kinds of crazy daemon action. Daemon action...who you gonna call? GREY KNIGHTS!!!

Other than that, hmm Ultrasmurfs for sure IMO. Word Bearers already have some long standing animosity against them. I've got my fingers crossed for a Space Marine tie in, as in I hope Titus may show up!

As for other chapters its anyone's guess really. But I wouldn't be surprised to see a Blood Raven appearance. Then again Relic may decide to keep the DMO40k universe seperate from the DoW universe or chuck em together. Who knows. *shrug*

OMG yer such a popular fluff groupie!! To hell with Grey Knights... you shouldn't see em at all... if you do it should be like a single combat squad of them... very rare. They should be npc's that arrive in an epic fight with a daemon... that's it.

Blood Ravens? pfft!!! Might as well broadcast... "I got into 40k when it hit video games". Let's pay homage to the original chapters before we give the newbie trash any space.

Imperial Fists, Crimson Fists, I can see.. they are brothers of Dorn. I think Blood Angels and Dark Angels should have a place before any others... Lets use chapters that have good aesthetics.. good history... and above all... Badd@ssness. Grey Knights are badass but they're never around in mass. Blood Ravens are not badass.. they're video game trash.

Actually, thats not far from the truth for me! XD! I've only recently gotten into the fluff. Although to be fair I had 'Space Hulk' boardgame when I was like...11.

I think Blood Ravens may be there, exactly because they are videogame trash rofl! This is after all, another video game!

Besides, I sadly don't know enough about WH40k stuff. My knowledge consists of videogames, reading wikis/forums, read 8 books so far of which 3 of those are about the grey knights. I hope you'll understand my bias.

I could see Crimson fists for sure and Blood angels as well, I would WANT Imperial Fists, but since GW has given them almost no fluff post-heresy, it probably won't happen.

Yea tbh, its a shame that a lot of legions are just 'off the map' post Heresy. Would be nice to see more legions put back on the map.

Are the Fists not just Garrison monkies in banana suits now? Kidding kidding, no no honest!

I like to see more of the Chaos Chapters too than Word Bearers or World Eaters, as I said though for lore reasons I doubt it. MMmm if the Sargos Sector is really near the Eye, how about the lost Space Wolfs Company? Now there is a happy dreaming.

^
Agreed, I was hoping that they would implement a Chaos legion/warband that was a little different than the vanilla CSM, but hopefully Vigil will suprise us!

Probably.

Not Blood Ravens however, they're Dawn of War exclusive. Expect Ultramarines or one of the Chamber Militants (Grey Knights, Death Watch, Sisters of Battle).