you can join into a pool of 50-100 people and there will be two clans that everyone will bide gold, dark elixir or elixir on and what ever clan wins the people who bid on that clan will get double what they bid but you can only bid what your clan castle can hold because it goes into that.
ex. I bid 10,000 gold on MEGA they win I get 20,000 gold in my clan castle.
ex. I bid 1,000 dark elixir on MEGA they lose I lose 1,000 dark elixir just from my storage (thats where the bidding money comes from not your clan castle)
and maybe you could bid trophies but you don't get double you get a smaller percentage and with that you could take the trophies to a hole new level!!!