Balduvian Frostwaker — ruling 1

A noncreature permanent that turns into a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn’t matter how long the permanent has been a creature.

Balduvian Frostwaker — ruling 2

Balduvian Frostwaker’s effect has no duration. The snow land is a creature as long as it’s on the battlefield.

Balduvian Frostwaker — ruling 3

If an affected land later loses the supertype snow, Balduvian Frostwaker’s effect doesn’t end. The land will remain a creature.

Balduvian Frostwaker : règles, fonctionnement et interactions (MTG)

Balduvian Frostwaker 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 snow land becomes a 2/2 blue Elemental creature with flying. It's still a land.

How it works : Balduvian Frostwaker

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn’t matter how long the permanent has been a creature.
No other card is named in this ruling.
#2July 15, 2006· Wizards of the Coast
Balduvian Frostwaker’s effect has no duration. The snow land is a creature as long as it’s on the battlefield.
No other card is named in this ruling.
#3July 15, 2006· Wizards of the Coast
If an affected land later loses the supertype snow, Balduvian Frostwaker’s effect doesn’t end. The land will remain a creature.
No other card is named in this ruling.