How about reducing the HP of the Guardian stones...
I mean... you have 2 guardian stones and ea has 400m? Plus there are different flags on the castle so the guild can easily warp in different territories inside the castle. So what I'm saying is 400m hp in ea of the guardian stones is way too BIG! Who else agrees?
Maybe 150 Mil for the stones will do... Because defenders just warp there and cast Sanctuary and safety wall..