Building Upgrades

Was thinking that in future quests or adventures we could have a reward of building upgrade buffs. 1 buff would instantly upgrade a building 1 level. They could also be included in the Mysterious Boxes from events or to buy with event resources. They could also be tradable. Basically introduce them somehow into the game but not to make them too easy to get. If they were to sell them for event resources we would have a limit on how many we could buy.

For those players that have all their buildings maxed, they could at least have something else to play for and sell the buffs.

go for it, brilliant