Man, Red Corsairs seems like a great idea. I mean, having Alpha Legion as a faction like this seems weird. This doesn't seem like a game with much room for infiltration to the point that Alpha Legion really go with it. On the other hand, it feels weird to take just ONE of the sides that follow a specific chaos god.. But Red Corsairs fit everything pretty great, tbh.
The Alpha Legion uses infiltration among a lot of other strategies; their true strength is intelligence and information manipulation - which in turn is used to deceive the enemy by all possible means - while their main weakness resides in their lack of specialized units (i.e. they are perfectely capable of frontal assault... if everything goes just as planned of course). I think that such control of the information and sabotage skills could be interesting to implement in EC (advanced auspex/minimap, larger access to standard supplies (ammo, grenades, etc.) on the battlefield, access to mines and explosive charges, etc.)
Red Corsairs. Shows that more modern Astartes are just as succeptable to the lure of power as their legionnare antecedents.
Welcome to the Iron Warriors, initiate. I hope you join me and reform the raptors, since many of my Brothers were lost in the siege of Castellax.
I like the thousand sons being up front, then I'd make a note of executing anyone of them that I can, just to rub it in. . I also like the alpha legion, just cuz I like them, but it would also help balance more I think. There are a decent number of fans that would choose chaos if they were available, then having all those players (maybe) choosing the imperium side as default. That way they feel like the good guys still but are still fighting for chaos in the game. I want to win but I assume the loyalist side is going to have the numbers. This should help a little. Love the world eaters. I think they should be in but doesn't break my heart if they aren't. Emporers children are my favorite chaos legion. Not sure why but have always liked them.
Please do not discount our fellow Battle Brothers whom dwell within the Maelstrom, The Red Corsairs might not be seen as truly Chaos but our brethren have earned their place among us nonetheless, they oppose those Imperium scum with the same hate as we, but are usually overlooked as true Chaos Space Marines, they might not worship our gods, but at least they do not worship that false emperor neither My Emperor's Children Noise Marines have a saying, "If we are bad at playing live, at least we should look good, while playing badly live" It is so subtle and pleasing, that the litter left the nest with contempt for their parent