I finally managed to advance to the Gold III League, it was not easy at all but if we play carefully it is possible to advance to higher leagues. It's very difficult to play in the modern format, the matchups are very unfair but it's still fun to play. I got 11 chest rewards for unlocking Gold III and opened them.
I guess I have no chance today, the rewards I got from the 11 chests are almost worthless. I'll try my luck with the Major chests and I'm buying 20 Major chests now, let's see what comes out of them.
I got 30 Reward cards, 5 Rare and 25 Common, from 20 Major chests, I guess I wasn't that unlucky, I'm happy with what I got from the Major chests.
There are about 4 days left in the current season and I will continue to fight to unlock Gold II.
I hope you get great rewards. Best of luck to everyone.