Sunderflock — ruling 1

If an Elemental on the battlefield has {X} in its mana cost, X is 0 for the purpose of determining its mana value.

Sunderflock — ruling 2

To determine Sunderflock's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases, then apply any cost reductions. Sunderflock's mana value remains unchanged, no matter what the total cost to cast it was.

Sunderflock — ruling 3

Once you announce you're casting a spell, no player may take actions until the spell has been paid for. Notably, opponents can't try to remove Elementals you control from the battlefield at that time.

Sunderflock — ruling 4

Once you determine the cost to cast Sunderflock, you may activate mana abilities to pay that cost. If the greatest mana value among Elementals you control changes while activating mana abilities (probably because you sacrificed one or more Elementals), the cost to cast Sunderflock remains what you previously determined.

Sunderflock : règles, fonctionnement et interactions (MTG)

Sunderflock 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

This spell costs less to cast, where X is the greatest mana value among Elementals you control. Flying When this creature enters, if you cast it, return all non-Elemental creatures to their owners' hands.

How it works : Sunderflock

Original English text — Wizards of the Coast / Scryfall

#1November 17, 2025· Wizards of the Coast
If an Elemental on the battlefield has in its mana cost, X is 0 for the purpose of determining its mana value.
No other card is named in this ruling.
#2November 17, 2025· Wizards of the Coast
To determine Sunderflock's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases, then apply any cost reductions. Sunderflock's mana value remains unchanged, no matter what the total cost to cast it was.
No other card is named in this ruling.
#3November 17, 2025· Wizards of the Coast
Once you announce you're casting a spell, no player may take actions until the spell has been paid for. Notably, opponents can't try to remove Elementals you control from the battlefield at that time.
No other card is named in this ruling.
#4November 17, 2025· Wizards of the Coast
Once you determine the cost to cast Sunderflock, you may activate mana abilities to pay that cost. If the greatest mana value among Elementals you control changes while activating mana abilities (probably because you sacrificed one or more Elementals), the cost to cast Sunderflock remains what you previously determined.
No other card is named in this ruling.