Board Thread:General Discussion/@comment-33060628-20170909002820/@comment-33728484-20170909005521

You have some great cards, but if I were you I'd focus on completing the Quests, in order to improve your rank, which will improve your max STA level and your team cost. The Quests will also give you plenty of dragon stones, which you'll need to summon other cards.

P.S. What team have you been using?

P.P.S. the "Super difficulty" stages of Dokkan events give out 7 medals, so you'll only have to do them 11 times, it won't take you months. But they do require solid teams - plural because each event is different - and a good amount of stamina.