If you pause at 0:35 in this video:
Halo 4 Coverage Trailer
Or look at the bottom right of this screenshot:
Assault Rifle and Gametype
You will see Regicide UR and M-Slayer UR, respectively. What I want to know is, what does UR stand for. And what would be the alternative? Also, what would M-Slayer be? I can’t think of anything that these would stand for! It’s gotta be some cool aspect of the gametype.
Under Review? It could be a beta type of the game type for Halo 4 and not the final version.
> Under Review? It could be a beta type of the game type for Halo 4 and not the final version.
Yeah but in a different screenshot I saw one that said “BR Slayer”, and it didn’t have a UR next to it. So the UR could be some type of rifle? 
343 said that the gametypes you see are a mish-mash of several feautures from several gametypes, for testing purposes. I wouldn’t read to deeply into them if I were you.