Off Balance — ruling 1

The ability only does something if used before attackers or blockers (as appropriate) are declared during a turn. If used after the creature is declared as an attacker or blocker, nothing happens.

Off Balance : règles, fonctionnement et interactions (MTG)

Off Balance 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

Target creature can't attack or block this turn.

How it works : Off Balance

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
The ability only does something if used before attackers or blockers (as appropriate) are declared during a turn. If used after the creature is declared as an attacker or blocker, nothing happens.
No other card is named in this ruling.