Can Rhasa the Sunderer be reduced to 0 energy cost but still require one Chaos Power to play?

Ruling: Yes, Rhasa can be reduced to a cost of 0 Energy but still requires one Chaos Power to play it.

Nuances:

• You can exhaust a rune to float energy before paying the power cost, though this would result in 1 floating energy if the energy cost is already reduced to 0
• The reduction only applies to resources being paid from the rune pool, which is separate from using your runes
• Costs are not paid directly from your runes