Swamp Attack 2 - one year later

 So, I've done the daily gift one year straight because of the Paywall. Let's see if that was enough:

upgrade from clvl 3 -> 4 costs 25 gold + 15 card of the character

upgrade from clvl 5 -> 6 costs 50 gold + 20 card of the character

upgrade from clvl 10 -> 11 costs 1500 gold + 200 card of the character

upgrade from clvl 11 -> 12 costs 2500 gold + 250 card of the character

upgrade from clvl 12 -> 13 costs 5000 gold + 400 card of the character

I already ran out of cards for Slow Joe. Have 47 card out of 400. After 1 year.

And this will also be the last character level I'll be able to unlock, given the upgrade will cost 5000 gold. This is ridiculous.

Means the limiting factor is the cards, which can not even be grinded for.