Arena Chess is an RTS dueling game that's been specially created for mobile devices so you can play in vertical format. Like DOTA, this subgenre was born as a 'mod' and lets you face other players on the Internet.
The battle system in Arena Chess is identical to other titles in this genre. The battles are divided into two phases: in the first one you can use your money to buy new units and deploy them on the battlefield, while in the second one you'll see how the fighting develops. Depending on the result of this confrontation, you'll get more or fewer coins, and use them to again get new troops or upgrade the ones you already have. That done, a new round will start. The person who has the most points when all the rounds end wins the game.
In Arena Chess you'll find dozens of different units, each with its own unique attributes and skills. Many of your troops' abilities can also create synergies with other units, which makes learning to combine them essential to winning. One of the most important things to keep in mind is if at some point you have three equal units, you can merge them to create a much more powerful one.
Arena Chess is an excellent take on auto-chess focused directly on Android devices, and letting you play in vertical format. Plus the game has very good graphics and a nice variety of creatures and characters.