Here is the best (fullproof) and funnest combination to use in the death room.

Primary: LAW
Secondary: (any)
Support 1: Fire nade
Support 2: Gas nade

This is good when your whole team has it especially. Think about it in the cramped death room, 8 people throwing fire and gas nades will surely hit them with at least one kind. It will usually swindle their HP down to 70 at least, and then BAM you hit them with a LAW. Since the LAW has spread damage this is very easy. If your whole team has this you will always win. Because what happens is you throw all your nades which kind of makes a wall for your opponent, then your teammate goes throught the wall and extends it by throwing their nades then your opponents will be like screw it and run through the fire/gas and BAM your team sends a bunch of LAWS flying at them, then you van pick up their gun if you run out of ammo.

It's a fullproof plan I just never got anyone to do this because they were to concerned about their KDR or they were just to stupid to understand the genious of this plan.