In playing through the sample game I noticed something troubling about some of the current card setups. The Persist costs are far too low. Many cards, like Immortal Blessing, which adds a 5 DR to the target, is relatively cheap to maintain at a persist cost of 1. This should probably have a persist cost of 2 or more. Persist is an interesting ability I'd like to have on more cards simply because it allows more to be done with a smaller sized decks.
This got me thinking in general about card costs and what I'm going to have to do to balance them. Its going to be a complicated mess trying to get everything at that sweet spot, where the card is worth the cost, but not underpriced. Then on top of that I have to consider the special abilities of each class in these costs.
This is really where it gets interesting and we have to start differentiating the cards. Each class has a gimic. The Rogue is all about avoiding attacks, generating stealth points and dealing burst damage once everything is set up. The Warrior is all about defenses, batlefield control (with taunt) and staying alive. The Priest is all about healing, damage reduction, and minor buffing. Finally, the wizard is about consistent damage, buffing, and some summoning.
Each class also has its drawbacks. Rogue, for example, is dependent on others to attack the target in order to deal a lot of damage. Priest is largely without direct damage, but is great in a support role. Warrior is great at keeping others alive and dealing melee damage, but lacks little direct damage that is not subject to defense, and will often take a beating. Wizard is unique in that unless it prevents the effect, most of his powerful abilities are exiled after cast, meaning as the game continues, they will have less and less available (as exile persists throughout the game, and discards are eventually reshuffled).
There are a wide variety of abilities and effects that each class has access to, which makes balancing difficult. For example, a warrior card that deals direct damage or overcomes defense is probably more valuable than the equivalent damage in a wizard card. This causes direct balancing problems. There are some general guidelines. Each class has a 1 cost card that adds 5 of their resource (faith points, spellbook pages, stealth or block), as well as a zero cost card that adds an extra tapped "mana" to their pool (though this should probably be a 2 cost card as it bypasses the normal one per turn addition of "mana" I need to figure out if I like the increased speed the card adds).