Ambitious Farmhand // Seasoned Cathar — ruling 1

A creature has different power from another if their powers are different numbers. For example, a 1/1 creature and a 2/1 creature have different powers.

Ambitious Farmhand // Seasoned Cathar — ruling 2

For three creatures to have different powers from one another, each of their powers needs to be different. A 1/1 creature, a 2/1 creature, and another 2/1 creature aren't three creatures with different powers, even though both 2/1 creatures have different power than the 1/1 creature.

Ambitious Farmhand // Seasoned Cathar — ruling 3

Many coven abilities, such as that of Dawnhart Wardens above, are triggered abilities with intervening if clauses. You must control three or more creatures with different powers at the time the ability triggers and at the time the ability tries to resolve. They do not, however, need to be the same set of creatures in both cases.

Ambitious Farmhand // Seasoned Cathar : règles, fonctionnement et interactions (MTG)

Ambitious Farmhand // Seasoned Cathar 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

When this creature enters, you may search your library for a basic Plains card, reveal it, put it into your hand, then shuffle. Coven — : Transform this creature. Activate only if you control three or more creatures with different powers. Lifelink

How it works : Ambitious Farmhand // Seasoned Cathar

Original English text — Wizards of the Coast / Scryfall

#1September 24, 2021· Wizards of the Coast
A creature has different power from another if their powers are different numbers. For example, a 1/1 creature and a 2/1 creature have different powers.
No other card is named in this ruling.
#2September 24, 2021· Wizards of the Coast
For three creatures to have different powers from one another, each of their powers needs to be different. A 1/1 creature, a 2/1 creature, and another 2/1 creature aren't three creatures with different powers, even though both 2/1 creatures have different power than the 1/1 creature.
No other card is named in this ruling.
#3September 24, 2021· Wizards of the Coast
Many coven abilities, such as that of Dawnhart Wardens above, are triggered abilities with intervening if clauses. You must control three or more creatures with different powers at the time the ability triggers and at the time the ability tries to resolve. They do not, however, need to be the same set of creatures in both cases.
No other card is named in this ruling.