If Player A plays Hidden Blade on a unit, can Player B play Discipline at reaction speed on another unit to draw a card, and if Player B draws a Defy from Discipline, can they play that Defy targeting the Hidden Blade?

Ruling: Yes, Player B can play Discipline in response to Hidden Blade, and after Discipline resolves and they draw a card, they can play Defy (if drawn) targeting the Hidden Blade before it resolves.

Sequence:

• Chain 1: Hidden Blade is played, priority passes
• Chain 2: Discipline is played, priority passes
• Chain 1: Discipline resolves (player draws from Discipline)
• Chain 2: Defy can now be played targeting Hidden Blade
• After all players pass priority, Hidden Blade attempts to resolve (or is countered by Defy)

Nuances:

• Discipline must resolve first before the card is drawn, so the player draws the card before getting another chance to react to Hidden Blade
• After each item on a chain resolves, priority passes to give everyone a chance to react
• Players can continue adding reactions as long as they have energy and cards, keeping items at the same chain level