Does Merchant's triggered effect (when moving to battlefield) happen before Showdown/Combat, and can opponents react to it?

Ruling: Merchant's trigger happens before Showdown begins, so you discard/draw before getting priority to play actions during Showdown. Opponents can react to the Merchant trigger itself.

Sequence:

• Merchant moves to battlefield and triggers
• Opponents can react to the trigger (it goes on the chain)
• Trigger resolves (discard/draw happens)
• Showdown begins with action priority

Nuances:

• If Merchant is removed (e.g., by Gust) in response to its trigger, the discard/draw still happens because the ability is already on the chain and doesn't require information