The skill tree is Laid out into three tiers. There is the basic tier, consisting of only basic attacks, the first tier class abilities, consisting of basic abilities for each class (Fighter, Rogue, Cleric, Mage) and the second tier, which are advanced abilities based off of the class tier.
The first iteration of these abilities were as follows
3x movement (before movement change)
3x basic attack (1 damgae)
T1: (2x of each card)
3 attack damage
1 poison damage/turn (2 turns)
3 damage blast