Does Ka'sai's ability pay for a card's power cost, and if so, does it reduce the number of runes that need to be recycled?

Ruling: Ka'sai's ability provides 1 power of any color that can only be used to pay for Spell cards. This power can substitute for recycling one rune, but does not pay for energy costs.

Sequence:

• To play a spell card, you must pay both its energy cost and its power cost separately
• Ka'sai's ability provides 1 power (of any color) that counts toward the power cost
• You still need to pay the full energy cost through other means
• If a spell needs 2 power, you can use Ka'sai's 1 power plus recycle 1 rune (instead of recycling 2 runes)

Nuances:

• Ka'sai's power can ONLY be used for spell cards, not other card types
• The power must match the color requirement of the spell (Ka'sai can provide any color)
• Power and energy are separate costs - Ka'sai only helps with power, not energy