Ok, now it's over for sure.
Once reached the 10th league, the cpu move first and with high level cards.
So if you don't have a massive amount of blue card at the maximum level, you simply jump on 10th league, loose the first match, jump back on the 9th league, win the match and jump in the 10th and go on looping in this way.
There is no way to increase the card deck. All the cards coming from the shop are green and low values. It takes ages to go on without spending money. But also if you buy the "Team of cocksucker" you receive cards not well usable (poor combos, low defense value). You have to buy a large amount of gems and buy many gold box from the shop.
Actually to win the 10th league you should have all the card in the deck with 30-35 of defense in order to have "some" chances to win.
For me it's over.
Have fun.