Here's an easy strategy if you have trouble with the bots: use recruits/sorcerer/school immediately, try to get two big attacks or two big castle-builder moves, then build up resources until you can use those two moves consecutively. The bots don't respond well when you make two huge moves in a row.
Magic Defense is a nice idea, but there isn't much strategy if the opponent is aware that it is being used (except for using a low-resource attack). It would be nice if it was disguised as something, like a random attack or castle build.
Loved the first one. For this new one, the graphics/animation are a nice upgrade, as are the new cards, but the whole interface is confusing. Resources shouldn't be in a single row, but in several smaller rows to easily look them up. Text wouldn't hurt either, or different colors. Card info should appear with just a mouse hover. Just fix the UI, please!
 "Penguin Overlords"){kind=icon}
 "Not To Scale"){kind=icon}
 "Lucky Tower"){kind=icon}
 "Road of the Dead"){kind=icon}
 "Monster Slayers"){kind=icon}
 "Age of Defense"){kind=icon}
 "Vertical Drop Heroes"){kind=icon}
 "Blockage"){kind=icon}
 "Doeo"){kind=icon}
 "Castlewars"){kind=icon}
 "Epic Coaster"){kind=icon}
 "Castle Wars 2"){kind=icon}
 "Epic War 4"){kind=icon}
 "Best Friends Forever 3"){kind=icon}