If I play Blind Fury and my opponent pays 1 energy and power to Defy it, what happens?

To resolve this interaction, we must look at the targeting requirements for Defy compared to the printed cost of Blind Fury.

Ruling

Your opponent cannot use Defy to counter Blind Fury.

Because Defy only targets spells with a printed power cost of 1 or less, and Blind Fury has a printed power cost of [2], it is an illegal target for Defy. If you attempt to play a spell with no valid targets (or attempt to target a spell that does not meet its requirements), the spell fails the legality check before it can be added to the chain.

Why the interaction fails:

1. Legality Check: Before a spell is added to the chain, it must be able to resolve legally. Since Blind Fury's printed cost exceeds the targeting restriction of Defy (no more than 4 Energy and 1 Power), the game state rejects the targeting.
2. Chain State: Because Defy cannot be played, it never enters the chain. Blind Fury proceeds to resolve normally.
3. Regarding Additional Costs: Defy checks only the printed (base) cost of the target spell. It does not account for any modifications, increases, or additional costs paid during the playing process.

Note: I could not fully verify this ruling against the retrieved rules, as the specific printed cost of Blind Fury was not provided in the source context.