Magic Crystal

You get magic crystal from crystal mines.
Each hour, you gain one magic crystal for every crystal mine your union holds.
They are needed only for upgrading your weapon and armor technology, above level 10.
Approximately no more than 5k magic crystals are needed to upgrade Cav4 to level 30, and no more than 80k for level 40.
Prior to level 40 structures, a player never need more than 100k magic crystals (5k * 10 types * 2 {weapon/armor}). But now, to upgrade all, a player will not need have more than 1.6 million crystals. To upgrade only 3 types, no more than 480k magic crystals will be needed.

I choose to write about this now because tomorrow, there's an event to compete for the crystal mines. However, there is a bug that may cause some confusion. Usually, the number of magic crystals you have is shown on the top banner (beside where it shows the number of gold coins you have). It also shows the number of crystal mines your union holds. A bug exists that when you get more than 1 million magic crystals, those counts disappears from the banner.

There is an easy workaround. To see the number of crystals (and the number of mines your union hold), click on Union and on the Union Info tab, you should see on the bottom left a count of the magic crystals you have and in parenthesis, the number of crystal mines your union holds.

Good hunting tomorrow.