Fuel

Fuel is an upgrade that increases the duration of the player's Pickaxe Power by 10% per level. Up to 20 upgrades can be purchase, and they cost 750 Coal(1.0) / $0.99(1.0) / 25 Runic(2.0) each. In Version 3.0, it was replaced by the Pickaxe Fuel Skill in the Player Skill Tree. Upon updating to Version 3.0, any Fuel upgrades the player had purchased are applied to the Legacy Relic.
 * Description(1.0): Permanently increase On Fire duration by an additional 10%