If I play Cleave and my opponent plays Defy on it, then I play Defy on their Defy, does my Cleave resolve?

Ruling: Yes, your Cleave resolves because the opponent's Defy was countered and never resolved.

Sequence:

• You play Cleave
• Opponent plays Defy targeting your Cleave
• You play Defy targeting opponent's Defy (before it resolves)
• Your Defy resolves, countering opponent's Defy
• Opponent's Defy never resolves
• Your Cleave resolves

Nuances:

• You must react to the first Defy before it resolves. If the first Defy resolves, it removes the card from the chain immediately and a second Defy played afterward would not help.