Bro Slayer: This new gametype consists of Team Slayer with co-op style spawning, featured on a variety of maps in Team Slayer, Big Team Battle and Noble Map Pack. Similar to Invasion spawning you can cycle through teammates or choose from your backfield spawns, but watch out for backfield spawn campers!
I don't think very many bro's play Halo, especially since BO has come out. But still. As for Noble Map Pack I have it, but can't really comment as my Gold sub expired so I'm stuck doing SP for now. (Not that I mind. I actually rather like the Halo: Reach campaign.)