If Yasuo attacks and triggers his ability ('When I attack, deal damage equal to my Might to an enemy unit here'), but the opponent plays Hidden Blade to kill Yasuo before the trigger resolves, does Yasuo still deal damage?

Ruling: Yasuo does not deal damage. When Hidden Blade resolves and kills Yasuo before his trigger resolves, Yasuo is no longer on the battlefield, so his ability cannot deal damage.

Sequence:

• Yasuo attacks and his trigger goes on the stack
• Opponent plays Hidden Blade (which was face down at the battlefield being attacked)
• Hidden Blade resolves, killing Yasuo
• Yasuo's trigger tries to resolve, but fails because Yasuo is dead

Nuances:

• The ability fails because "here" and "my Might" return null (not 0 for Might) when Yasuo is no longer on the battlefield
• This is different from Magic: The Gathering, which uses last known information. Riftbound does not have last known information rules, so the ability cannot use Yasuo's previous stats