Originally Posted by the9quad
What those guys said above me +1, I think it is the best myself. Other fun card games are Kard combat and shadow era which are both free, those have booster packs for IAP, but you can definitely play the free to see if they are your cup of tea. Orions2 is also good but dead.
I agree on Kard Combat, although the multiplayer has some issues that I'm sure will be fixed. I never got into Shadow Era, thinking it was going to be very expensive to build a competitive deck. That is one of the things I love about Ascension. All players use the same deck. I can't wait for the Fallen expansion. Ascension is one of the relatively rare Iphone games that is console quality. In hindsight, I would have paid at least 10 times the asking price for it.
One under the radar card battle game I have enjoyed is Alien Menace. Definitely worth checking out if you enjoy solo campaigns.