Shop is where you can check and buy optional in-app-purchases. It also contains the Restore Purchases button- handy when you upgrade your hardware or proliferate iMtG to other devices.
I'll Have It All
Scanner
Disable Ads (http://imtgapp.com/forum/index.php?topic=16858.0)
Offline Cache
Unlimited Decks (http://imtgapp.com/forum/index.php?topic=16857.0)
Card Rulings
Card Translations
Trading