I've been debating more on this. It's almost a "given" that players will detest any progression method that encourages premium content, for the reasons I outlined below. But what if we separated the two entirely?
Here's what I'm thinking:
-Free version has ads, but unrestricted game
-Free version only has 1-3 deck slots
-Free version has an energy cap on campaign
-Free version earns X gold per game
-Free version has X% chance to find the essences to "upgrade" cards.
Two pay models:
-Aesthetic upgrades. There will be sketches of cards available, as well as possibly re-colorings. You can buy pretty cheap ($1 a card?)
-Subscription. Say $10/mo, with reductions up to say $5/mo for a year. Doing this one will unlock like 10-20 deck slots, and permanent ad reduction in-game. In fact, they might be purchasable on their own and you'll get a price reduction on the first premium month. While you're subscribed, you'll earn double gold, double chance to find upgrade stones, and no energy caps on campaign.
-MAYBE you'll be able to buy in-game currency with RL money, but if it's done it'll be purely so you can, it won't be the intended method to get cards.
It's tough to come up with models that facilitate a "fair" game between players. This is all speculation at this point, but I like to write down all my ideas.
Oh, and all cards tested now and attacking system known-bugs resolved. All that's left is barricades and then it's on to the fun stuff.
That's all for now