Blinding Beam — ruling 1

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.

Blinding Beam : règles, fonctionnement et interactions (MTG)

Blinding Beam is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

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.)

How it works : Blinding Beam

Original English text — Wizards of the Coast / Scryfall

#1June 7, 2013· Wizards of the Coast
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.
No other card is named in this ruling.