Blastin' and Relaxin' (500 cR)- Kill 50 enemies in any game mode in Reach.
Supporting Role (400 cR)- Earn 20 assists in Firefight Matchmaking.
Office of Not Dying (4000 cR)- Complete ONI on Legendary without dying.
Heroic Demon (2500 cR)- Kill 50 Elites in Firefight Matchmaking on Heroic or harder.
Total: 7400 Credits
Alright, as far as I know, this is the best day yet. And it's not going to be a fun day. Blastin' and Relaxin' can be gotten through the others, but if not: Forge up something crazy. Use your bloody imagination. Supporting Role, my best advice is to shoot to maim. Don't go for headshots, as tempting as they are. Have someone else pick them off quick before their shields regenerate though. The Office of Not Dying will take awhile, but here's what you do: play with a mate, and have him do go ahead, clearing out enemies. You should stay back well away from the fighting. Then, just switch places so he can get it. You can still get the challenge if your teammate dies and you live. Heroic Demon just takes some patience and luck. They may not always spawn, but when they do, just blast away. You'll get some of them for sure. Cheers!