Can you react to Draven Glorious Executioner legend ability?

Yes, you can react to the triggered ability of the Glorious Executioner (Draven) legend.

According to the Chain Rules, triggered abilities use the chain. When the condition "When you win a combat" is met, the ability is added to the chain, which creates a Closed State where players have the opportunity to play [Reaction] cards or abilities.

How it works:

1. Combat concludes: The combat resolution step finishes, and it is determined that you have won (only your units remain at the battlefield).
2. Trigger: The "When you win a combat" ability triggers and is placed on the chain.
3. Reaction window: Because the ability is now on the chain, both players may now play reactions.
4. Resolution: Once all reactions have been played and resolved (following LIFO - Last In, First Out), the legend ability resolves, and you draw a card.

As specified in the Showdown Flow, combat ends when both players pass with focus on an empty chain. The legend ability triggers at that moment, allowing for a reaction window before the draw occurs.