Does Navori Bladescout's ability target, and can you react with Cub from hidden to give the buff to Cub itself?

Ruling: Navori Bladescout's ability does target. You cannot react with Cub from hidden to give the buff to Cub itself.

Sequence:

• The trigger goes onto the chain and finalizes
• Targets are picked during finalization
• Your first priority window is after finalization (after targets are already picked)

Nuances:

• You can react to the trigger going onto the chain, but your priority window comes after target selection has already occurred