I don't know if there was this prelude once, I didn't find it, but I think it is a proposal of solid defense quality. Heroes on lvl 5+ get special power in attack, which is very useful, but I think it would be nice to see the same in the defense of the base. King, Queen and Champion when they spend 50% helt or 30% to automatically use their power they already have in attack. Warden is turning into a building so he doesn't even need immunity, but these three heroes would be very interesting and a little difficult to attack the entire base if they used power in both defense and attack.