In a 3-player game, if Anivia attacks a battlefield with a hidden Hidden Blade, can you activate Hidden Blade in response to kill Anivia before her attack ability resolves, and would that prevent her ability from affecting your units?

Ruling: You can activate Hidden Blade as a reaction to Anivia's "when I attack" ability and kill her before it resolves. If Anivia dies before her ability resolves, the ability will not affect your units.

Sequence:

• Anivia attacks the battlefield
• Anivia's "when I attack" ability triggers
• You can react by activating Hidden Blade to kill Anivia
• If Anivia dies, her ability tries to find "here" and cannot, so it fails to resolve

Nuances:

• This works specifically because Anivia's ability references "here" (her location)
• Riftbound has no concept of "last known information" - if a unit is gone, abilities referencing its location cannot find it
• This differs from games like Magic where abilities can resolve even if the source is removed