Ghirapur Guide — ruling 1

Once a creature with power 2 or less has blocked a creature, activating Ghirapur Guide's ability won't change or undo that block.

Ghirapur Guide — ruling 2

Once a creature with power 3 or greater has blocked the target creature, changing the power of the blocking creature won't change or undo that block.

Ghirapur Guide : règles, fonctionnement et interactions (MTG)

Ghirapur Guide 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 you control can't be blocked by creatures with power 2 or less this turn.

How it works : Ghirapur Guide

Original English text — Wizards of the Coast / Scryfall

#1July 13, 2018· Wizards of the Coast
Once a creature with power 2 or less has blocked a creature, activating Ghirapur Guide's ability won't change or undo that block.
No other card is named in this ruling.
#2July 13, 2018· Wizards of the Coast
Once a creature with power 3 or greater has blocked the target creature, changing the power of the blocking creature won't change or undo that block.
No other card is named in this ruling.