Consume stacked Abilities to enhance base values

Now that we can accumulate multiples of the same ability, the next reasonable step would be to create a skill tree system, where players can consume their stacked abilities to increase their base stats.

So whenever you enter a dungeon, your abilities are improved based on how much you leveled it up, from the start.

In this image, you can see the skill tree for the Renew ability.
You can spend stacked Renew abilities to improve Heal Radius, Heal Stack, Heal Amount and Renew Cooldown.
Same logic applies to all the other abilities.