Artifact cards are immensely powerful cards that lets players bend or even in some cases break rules for a cost. Also belongs to the Equipment sets too. That little thing that has an Initiative cost, is the key. Every action you take, well almost every action has some initiative cost. There are also ways to get more initiative back, potions, not taking actions, etc.

The Soul of Stars actually has a history of RP back in my past and was something I wanted to include in the game. The Jaguar tribe held it as a rather sacred artifact.