The players set up in a stack at a distance that should not be more than half the throwing distance of the weakest thrower. It's better to to the drill with several stacks competing against each other in order to add intensity. You need to be a minimum of 4 players on each stack.
Player 1 throws a backhand to Player 3, avoiding Player 2.
Player 3 passes to Player 2.
Player 2 throws to Player 4 avoiding Player 3. and it basically goes on like that.
4 to 3
3 to 5
5 to 4
4 to 6
6 to 5
5 to 7
7 to 6
6 to 7
7 to 5
5 to 6
6 to 4
4 to 5
5 to 3
3 to 4
4 to 2
2 to 3
3 to 1
1 to 2
2 to 1. This completes the play. You repeat it on the forehand, hammer, you can even add thumber or scoober if you've got good throwers. The aim when you've got different stacks is to finish the play first obviously.