Can you use Defy on Sky Splitter if its cost is reduced to 4 or less?

Ruling: No, you cannot use Defy on Sky Splitter even if its cost is reduced to 4 or less. Defy looks at the printed energy cost, not the modified cost.

Nuances:

• This same principle applies to other cost-reduction interactions - for example, Kai'sa cannot cast Sky Splitter from trash for a value of 2 even though Sky Splitter's cost can be reduced.