Shadowverse

At first, I was still getting the hang of it, and I lost a thousand rating points. Then I plateaued, and now I've climbed back up with a win streak. I finally perfected my portal deck – I removed the golems, the random artifact amulets (for some reason, they didn't work), and brought back the flying swordsmen. I crafted a second Deus, and it took off. The dragon is also very good – I got daily quests for it, and it turned out that even my clunky deck with one Sah and one "still no match for Mr. Dragon" works well. Shadow and runes have some cool tricks to counter it – resurrecting Khavy and endless Professor A through 4/4 illusionists, but it seems like they only work against the dragon.
For the portal, you basically only need Deus from the legendaries; the rest are more like nice bonuses. Although I've seen a build with Chronos, apparently as a replacement for it. And Bahir also works well; sometimes it saves the day.