Erizon
This is exactly my point. There is no way to avoid such exploit. If some guild is intend to capture some certain OP, they will do anything to achieve this goal. While defenders would have very limited amount of time to do the same, compared to the attacking guild. Not mention the need of constant swapping guilds to help your friends is plain stupid. Human nature is such that if there is a way to abuse something, there will be those who put forth as much effort as it takes to abuse that thing, to gain an advantage. If you have to wait two weeks before you can participate in a battle, people will swap guilds two weeks in advance. Or three weeks. Or four. Or whatever it takes.