Board Thread:Questions and Answers/@comment-34084605-20171228221407/@comment-31547802-20171228222320

No, sadly enough, once you've done the quest stages with 3 stars, there are no more dragon stones in that section. You can however get more by completing events, and most will have DS for completing their stages, as well as their missions. The Hero and Villian events that appear every weekend are the best for those. And then there are some stones you can get by doing each dokkan and strike stages at least once. However, after all that, all you really have are the login bonuses and whatever special missions they put in for a limited time.

Yeah, it gets slow. :(