When Hidden Blade kills Undercover Agent and the opponent draws 2 cards (one being Gust), can the opponent play Gust before the Undercover Agent's Deathknell trigger resolves?

Ruling: Yes, the opponent can play Gust before the Deathknell trigger resolves.

Sequence:

• Hidden Blade resolves, killing Undercover Agent and drawing two cards
• Deathknell trigger goes on the chain
• There is an opportunity window for Reactions (like Gust) before the Deathknell resolves
• After Reactions are played or passed, the Deathknell trigger resolves