Harvesttide Sentry — 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.

Harvesttide Sentry — 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.

Harvesttide Sentry — ruling 3

Harvesttide Sentry's triggered ability checks your creatures' powers both when it triggers and as it tries to resolve. If you somehow don't have enough creatures with different powers as it tries to resolve, nothing happens and Harvesttide Sentry can be blocked as normal.

Harvesttide Sentry — ruling 4

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.

Harvesttide Sentry — ruling 5

Once its ability resolves, removing one of the creatures with different powers won't allow a player to block Harvesttide Sentry with creatures with power 2 or less.

Harvesttide Sentry — ruling 6

The blocking restriction is applied only when blockers are declared. After the coven ability resolves, if a player blocks Harvesttide Sentry with a creature with power greater than 2, reducing that creature's power won't make Harvesttide Sentry unblocked.

Harvesttide Sentry : règles, fonctionnement et interactions (MTG)

Harvesttide Sentry 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

Coven — At the beginning of combat on your turn, if you control three or more creatures with different powers, this creature can't be blocked by creatures with power 2 or less this turn.

How it works : Harvesttide Sentry

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
Harvesttide Sentry's triggered ability checks your creatures' powers both when it triggers and as it tries to resolve. If you somehow don't have enough creatures with different powers as it tries to resolve, nothing happens and Harvesttide Sentry can be blocked as normal.
No other card is named in this ruling.
#4September 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.
#5September 24, 2021· Wizards of the Coast
Once its ability resolves, removing one of the creatures with different powers won't allow a player to block Harvesttide Sentry with creatures with power 2 or less.
No other card is named in this ruling.
#6September 24, 2021· Wizards of the Coast
The blocking restriction is applied only when blockers are declared. After the coven ability resolves, if a player blocks Harvesttide Sentry with a creature with power greater than 2, reducing that creature's power won't make Harvesttide Sentry unblocked.
No other card is named in this ruling.