Does Leona need to announce a target when her attack trigger goes on the chain, or does she pick the target upon resolution? Can a defender use Flash to remove the targeted unit in response?

Ruling: Leona announces the target when the attack trigger goes on the chain. The target is checked for validity again just before the effect resolves.

Sequence:

• Leona's attack trigger goes on the chain and a target is announced
• Opponent can respond with Flash (or other effects) on the initial chain
• When the trigger resolves, the target is checked for validity
• If the target is no longer valid (e.g., removed by Flash), no stun occurs and no buff is granted from Leona's legend

Nuances:

• The word "target" does not appear in print in Riftbound, but any time you make a choice, it's almost always going to function as a target
• Targets are announced when triggers go on the chain and checked again for validity just before resolution