Blue Dragon
Creature — Dragon
Flying
Lightning Breath — When this creature enters, until your next turn, target creature an opponent controls gets -3/-0, up to one other target creature gets -2/-0, and up to one other target creature gets -1/-0.
Steve Prescott
Magic Online Promos (PRM)
• #92686Rulings
The last two targets are optional, but the first target is not. If an opponent has at least one creature the ability could target, you must choose a target to get -3/-0. (Note that the last two targets can be any creature, not just one an opponent controls.)
(wotc • 2021-07-23)
Blue Dragon's Lightning Breath ability cannot target the same creature multiple times.
(wotc • 2021-07-23)
Rulings
The last two targets are optional, but the first target is not. If an opponent has at least one creature the ability could target, you must choose a target to get -3/-0. (Note that the last two targets can be any creature, not just one an opponent controls.)
(wotc • 2021-07-23)
Blue Dragon's Lightning Breath ability cannot target the same creature multiple times.
(wotc • 2021-07-23)