Blinding Beam
Instant
Choose one —
• Tap two target creatures.
• Creatures don't untap during target player's next untap step.
Entwine 
(Choose both if you pay the entwine cost.)
Doug Chaffee
Modern Masters (MMA)
• #7Rulings
The second mode affects all creatures during the player’s next untap step, including creatures controlled by other players (who may have untapped because of Seedborn Muse, for example) and creatures that weren’t on the battlefield when Blinding Beam resolved.
(wotc • 2013-06-07)
Rulings
The second mode affects all creatures during the player’s next untap step, including creatures controlled by other players (who may have untapped because of Seedborn Muse, for example) and creatures that weren’t on the battlefield when Blinding Beam resolved.
(wotc • 2013-06-07)