Maybe having enough money to pay lawyers to attack people. But yes, I think this would be awesome, and if it was successful enough, whenever large companies say 'oh, we only hold patents for defensive reasons' they could be pressured to donate them. Hmm thing is though, the countersue companies to stop them enforcing patents doesn't work so well for true patent trolls who aren't actually doing anything so probably aren't breaching patents (unless their patents breach patents, if that's possible).