Break Through the Line — ruling 1

If the creature’s power is greater than 2 as the activated ability tries to resolve, the ability won’t resolve and none of its effects will happen. However, if the creature’s power is raised above 2 after the ability resolves, it will still have haste and can’t be blocked that turn.

Break Through the Line : règles, fonctionnement et interactions (MTG)

Break Through the Line 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 with power 2 or less gains haste until end of turn and can't be blocked this turn.

How it works : Break Through the Line

Original English text — Wizards of the Coast / Scryfall

#1November 24, 2014· Wizards of the Coast
If the creature’s power is greater than 2 as the activated ability tries to resolve, the ability won’t resolve and none of its effects will happen. However, if the creature’s power is raised above 2 after the ability resolves, it will still have haste and can’t be blocked that turn.
No other card is named in this ruling.