When Anivia attacks and triggers her ability to deal 3 damage to all units, can you respond with reactions like Smoke Screen or Hidden Blade before the damage resolves?

Ruling: You can respond to Anivia's attack triggered ability with reactions (like Smoke Screen) before it resolves. However, Hidden Blade can only be played from hand after the chain is empty (at action speed), unless it was already hidden at that battlefield.

Sequence:

• Anivia moves to the battlefield, triggering a showdown
• Anivia's attack triggered ability creates the initial chain
• Players can respond with reactions (like Smoke Screen) to this chain
• Once the chain resolves completely, the attacker gets focus first to play actions
• Then the defender can play actions (like Hidden Blade from hand)

Nuances:

• If Hidden Blade was already hidden at the battlefield, it can be played as a reaction to Anivia's trigger
• If Anivia is removed from the battlefield before her ability resolves, the ability does not deal damage because it specifies "here" and when it resolves, "here" refers to where Anivia currently is (the trash), not the battlefield
• Combat continues normally even if all of one player's units die during the showdown