Potions:  Used to grant experience to your heroes in order to increase their level.  Potions are earned by clearing stages, as quest rewards, and can be found in the store.
 Scrolls: Used to level up the skills of your heroes.  Scrolls can be found in the Tower mode and the store.
 Runes: Used to raise the Rune Rank of your heroes.  Whenever Runes are equipped to your heroes they provide a boost to that hero's stats.  Runes can be found by clearing stages and in the store.
 Shards: Used to unlock new heroes and increase the Stars of your existing heroes.  Shards can be found on specific stages, Progression Quest rewards, and in the store.