Talk:GAME Update V2/@comment-168.196.36.12-20190101105747/@comment-77.127.61.203-20190101124413

You get gems that give 10% bonus to the AT and HP of the card. If you have 4 gems, you can upgrade them to one gem that gives 25% bonus. I didn't try to upgrade more, but I guess that if you have 4 of the upgraded gems, you can upgrade them even more to a one better stone. You can then select a card and assign a gem to it. I only tried it with Rare and Epic, You can assign one gem to a Rare card, and two gems to an Epic card. Each gem has a colour (of the dungeon you got it from), and you can assign it to cards from the same colour. Red stones to fire cards, etc.

After you assigned a gem to a crd, you can destroy it to make place for a stronger gem for that card, or retrieve it for some rubies (in order not to destroy it).

I guess that the best way is to get a lot of gems, upgrade them to the max, and only then assign them to cards. But if you want to move faster in the beginning, assigning the +25% gems is good enough. If I'll make stronger gems later on, I will ust destroy the ones that I have assigned, and put stronger ones instead. BTW, upgrading 4 10% to one 25% costs 3000. I guess that upgrading 25% to a stronger gem may cost more gold.