When Yasuo, Remorseful attacks a battlefield defended by Ahri, Nine-Tailed Fox with a 4 might unit, what is the correct order for the initial chain, and can Discipline be played during initial chain formation?

Ruling: Yes, Discipline can be played during initial chain formation. The attacker adds their triggers first, then the defender adds their triggers, and then the defender has priority to react to their own trigger before the attacker can react.

Sequence:

1. Yasuo, Remorseful's "when I attack" trigger goes on the initial chain
2. Ahri, Nine-Tailed Fox's "when defending" trigger goes on the initial chain
3. Player A (defender) has priority to react to their own trigger with Discipline, which goes on the initial chain
4. Yasuo player would have priority to play a reaction before Ahri can play Discipline
5. Chain resolves in reverse order: Discipline resolves (unit goes to 6 might), Ahri trigger resolves (Yasuo goes to 5 might), Yasuo trigger resolves (defending unit takes 5 damage)
6. Chain fully resolved, priority goes to attacker

Nuances:

• The defender adds their triggers to the initial chain last
• Before the defender (Ahri player) can play Discipline, the attacker (Yasuo player) would have priority to play a reaction