Blasphemous Act — ruling 1

Although players may respond to Blasphemous Act once it's been cast, once it's announced, they can't respond before the cost is calculated and paid.

Blasphemous Act — ruling 2

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Blasphemous Act). The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.

Blasphemous Act — ruling 3

Blasphemous Act's ability can't reduce the total cost to cast the spell below {R}.

Blasphemous Act — ruling 4

The total cost to cast Blasphemous Act is locked in before you pay that cost. For example, if there are three creatures on the battlefield, including one you can sacrifice to add {C}, the total cost of Blasphemous Act is {5}{R}. Then you can sacrifice the creature when you activate mana abilities just before paying the cost.

Blasphemous Act : règles, fonctionnement et interactions (MTG)

Blasphemous Act 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 for each creature on the battlefield. Blasphemous Act deals 13 damage to each creature.

Complete guide

Blasphemous Act is a classic red board wipe that rewards you for being in a crowded game. It is a powerful tool for turning a swarm of creatures into a pile of ash for as little as a single red mana.

What it Does

Blasphemous Act is a sorcery that deals 13 damage to every creature on the battlefield. While its printed mana cost is nine mana, it features a cost-reduction ability that subtracts one generic mana for every creature currently on the battlefield, including your own and those belonging to your opponents.

How it Resolves Step by Step

First, you announce the spell and check how many creatures are on the battlefield to determine the cost. This cost is locked in before you pay; even if a creature leaves the battlefield while you are activating mana abilities (like sacrificing a creature for mana), the discount remains. Once cast, players may respond with spells or abilities. When it resolves, it deals exactly 13 damage to every creature simultaneously. Any creature with toughness 13 or less will typically be destroyed by state-based actions immediately after.

Common Mistakes

A common misconception is that the Mana Value of the spell changes based on the discount. The Mana Value of Blasphemous Act is always 9, regardless of how much mana you actually spent to cast it. Additionally, remember that the cost reduction can only reduce the generic mana portion of the cost; you must always pay at least one red mana ({R}) to cast this spell.

When to Play it

This spell is best utilized when the board is stalled with many small creatures. Because it counts all creatures, you can often cast it for {R} when there are eight or more creatures in play. It is an excellent way to reset the board before playing your own threats or to trigger abilities that care about creatures dying.

Interaction examples

Stealing and Sweeping

Insurrection

If you cast Insurrection first, you gain control of all creatures on the battlefield. Even though you now control them, the total number of creatures hasn't changed. You can then use those creatures to count toward the discount for Blasphemous Act. After attacking with your new army, you can cast Blasphemous Act for a low cost to ensure your opponents don't get their creatures back at the end of the turn.

Cascading into Destruction

Call Forth the Tempest

When you cast Call Forth the Tempest, its Cascade triggers twice. If you exile Blasphemous Act, you may cast it for free because its Mana Value (9) is less than Call Forth the Tempest (11). Later, when Call Forth the Tempest resolves, it will count Blasphemous Act as a 'spell you've cast this turn.' This will add 9 to the total damage Call Forth the Tempest deals to your opponents' creatures.

Guide written with AI from the official text and rulings. Official English text prevails.

How it works : Blasphemous Act

Original English text — Wizards of the Coast / Scryfall

#1November 10, 2020· Wizards of the Coast
Although players may respond to Blasphemous Act once it's been cast, once it's announced, they can't respond before the cost is calculated and paid.
No other card is named in this ruling.
#2November 10, 2020· Wizards of the Coast
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Blasphemous Act). The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.
No other card is named in this ruling.
#3November 10, 2020· Wizards of the Coast
Blasphemous Act's ability can't reduce the total cost to cast the spell below .
No other card is named in this ruling.
#4November 10, 2020· Wizards of the Coast
The total cost to cast Blasphemous Act is locked in before you pay that cost. For example, if there are three creatures on the battlefield, including one you can sacrifice to add , the total cost of Blasphemous Act is . Then you can sacrifice the creature when you activate mana abilities just before paying the cost.
No other card is named in this ruling.