Can you play Call to Glory using only a buff from your character if all your runes are exhausted (without having 3 runes available)?

Ruling: Yes, you can play Call to Glory with no runes available for energy if you spend a buff. Additional costs and base costs are calculated together when determining cost and paid at the same moment.

Sequence:

• Calculate total cost (either 3 energy OR 1 buff)
• Pay the chosen cost at the same moment

Nuances:

• You do not need to have 3 runes available if you are paying with the buff instead