Massive payoff option for Star generation and Vigor stacks, but keep in mind that there are other ways to turn Stars into damage more efficiently than this unless you're able to do a good job of stacking Vigor for it or able to Enchant it.
The ultimate payoff to a deck that can generate a lot of stars. Works really well with Royal Gamble. Scale the damage with Strength or Vigor for maximum effect.
At the start of your turn, add 1 random Colorless card into your Hand.
Forge 5. Draw 2 cards.
Deal 6 damage.
Forge 8. Put Sovereign Blade into your Hand from anywhere.
