If Skysplitter's cost is reduced (e.g., to only 1 red power due to having a 9 might unit), can it be countered by Defy?

Ruling: No, Skysplitter cannot be countered by Defy even when its cost is reduced. Defy always looks at the printed cost, not what was actually paid.

Nuances:

• This principle applies to anything that references cost - they all look at printed cost rather than modified or paid cost.