When a card with discard cost is discarded, does it cost its full printed cost or the alternative discard cost to play?

Ruling: When you discard a card with a discard cost, you pay the alternative discard cost (one red power), not the full printed cost.

Nuances:

• The discard cost requires power, not energy
• You can generate the required power by recycling a red rune or through any alternative method that generates red power
• You should not think of costs specifically as tapping/recycling runes - that's just one way to generate the required resources (energy/power)
• You can tap or recycle runes at any point during your turn to generate energy/power and use those resources later in the turn