How do runes work? What are energy and power? Can I recycle an exhausted rune?

Yes, each rune has two abilities, and you can use both of them in the same turn: You can exhaust a rune to produce 1 energy. Energy is used to pay numerical costs, and doesnʼt have a domain/color associated with it, even though the runes used to generate it do. You can recycle a rune (even an exhausted one) to produce 1 power of that runeʼs domain/color. Power is used to pay color symbol costs. Rune abilities have the Reaction keyword, which means they can be used anytime.