Whenever you have attained a lot of loot by whatever method, you of course put it to use for upgrading things, but you just attacked, and your gowipe won't be done for two hours. So you go play boom beach for like 1/2 an hour I don't care. You come back later, and you have almost enough loot to upgrade whatever, but you can't remember what it was,. Or .you might want to to make specific troops to donate, Go for base number 14. It has many uses and would be a small yet very beneficial addition to the game. Hit the mail button, and click the new fourth tab, write your note, get on with life.
