Main method of obtaining gems is by kill combos. Based on the combo length, enemies drop score items and finally gold coins and gems. This way the gem drop rate is directly skill based.
Gem and coin packs will be available as IAP. Gems are used at least for boosts and continues, everything else is still to be determined. Another possible use for gems that I can think of is buying a hero or two, in addition to the other methods (collecting items required for an unlock or buying heroes with gold coins).
Wow... long time since my last post. But hey, Ive recorded some gameplay videos straight from Power Heroes using Everyplay! You can find them here.
Very cool. I just love the visuals. In case I haven't already volunteered, I'd love to help beta test if you need it.