Board Thread:Warhammer 40k General Discussion/@comment-172.97.120.12-20160619182557

Hi, I'm new to warhammer 40k I just finished Painting my first Space Marine Tactical squad but I have yet to look into the rules in depth. But I was wondering if I could have a single marine or two from say Blood Angels in my tactical squad? Although arguably i could just paint one red just for looks.

I ask this because I was thinking I want to put a space marine paint job on a Sister of Battle and put her in the squad just to make the squad look more diverse. Is that allowed or is it completely against the rules? 