Ironclaw Buzzardiers — ruling 1

"Can't block" abilities apply only as blockers are declared. After Ironclaw Buzzardiers blocks, increasing the blocked creature's power won't make it become unblocked.

Ironclaw Buzzardiers : règles, fonctionnement et interactions (MTG)

Ironclaw Buzzardiers 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

This creature can't block creatures with power 2 or greater. : This creature gains flying until end of turn.

How it works : Ironclaw Buzzardiers

Original English text — Wizards of the Coast / Scryfall

#1September 25, 2006· Wizards of the Coast
"Can't block" abilities apply only as blockers are declared. After Ironclaw Buzzardiers blocks, increasing the blocked creature's power won't make it become unblocked.
No other card is named in this ruling.