Sneaking Guide — ruling 1

If the target creature’s power is greater than 2 as Sneaking Guide’s ability tries to resolve, the ability doesn’t resolve. However, if instead the creature’s power is raised above 2 after the ability resolves, it still can’t be blocked that turn.

Sneaking Guide — ruling 2

Once a creature with power 2 or less has been blocked, Sneaking Guide’s ability won’t cause it to become unblocked.

Sneaking Guide : règles, fonctionnement et interactions (MTG)

Sneaking 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 with power 2 or less can't be blocked this turn.

How it works : Sneaking Guide

Original English text — Wizards of the Coast / Scryfall

#1September 25, 2020· Wizards of the Coast
If the target creature’s power is greater than 2 as Sneaking Guide’s ability tries to resolve, the ability doesn’t resolve. However, if instead the creature’s power is raised above 2 after the ability resolves, it still can’t be blocked that turn.
No other card is named in this ruling.
#2September 25, 2020· Wizards of the Coast
Once a creature with power 2 or less has been blocked, Sneaking Guide’s ability won’t cause it to become unblocked.
No other card is named in this ruling.