Here's the setup:
9 Prot warriors, a handful of magi, and a pair of healers.
Improved spell reflection: You can reflect spells directed at allies
Glyph of Spell Reflection: Reduces cooldown by one second.
The overall result is that with 9 warriors and a 9 second cooldown, any cast can be reflected permanently.
One mage per team is the server while the rest have the job of AoEing the warriors to ensure that they have enough rage. The healers keep the warriors from dying.
Players can only wear gear without stats.
How to play:
The mage casts a nuke at an enemy warrior. Someone on the other team must reflect it back. Then the first team must reflect it back. Generally speaking you score when the other team gets hit.
Use standard volleyball rules, but adapted for the situation. Getting hit by a spell is counted like the ball falling on your side of the net. Getting hit but resisting is counted as if the other team hit it last and it fell out of bounds.
Rage generation vs. healing and regen: The mage in charge of rage generation is on the same team as the warriors they are AoEing, though not the same party since he needs to be able to attack. He must balance his mana usage and the need for healing with the need to ensure enough rage for a reflect.
Proper rotation: If someone screws up the rotation, you might not have a reflect ready next time the spell comes around.
Optional rule to make it interesting:
In addition to spell reflect, the warriors may use charge (however they cannot have the talent to use it in combat) and shockwave. Charging will allow you to prevent reflects and generate extra rage, however if may also put you out of range to reflect and cannot be used constantly. To prevent a win by mass-charging, there is a limit of two charges per bounce. Shockwave, well that could knock out the entire other team if they're grouped up too much, but at the cost of rage and positioning.