Whir of Invention — ruling 1

Improvise doesn't change a spell's mana cost or mana value.

Whir of Invention — ruling 2

When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Improvise applies after the total cost is calculated.

Whir of Invention — ruling 3

Because improvise isn't an alternative cost, it can be used in conjunction with alternative costs.

Whir of Invention — ruling 4

Improvise can't pay for {W}, {U}, {B}, {R}, {G}, or {C} mana symbols in a spell's total cost.

Whir of Invention — ruling 5

Improvise can't be used to pay for anything other than the cost of casting the spell. For example, it can't be used during the resolution of an ability that says "Counter target spell unless its controller pays {3}."

Whir of Invention — ruling 6

If an artifact you control has a mana ability with {T} in the cost, activating that ability while casting a spell with improvise will result in the artifact being tapped when you pay the spell's costs. You won't be able to tap it again for improvise. Similarly, if you sacrifice an artifact to activate a mana ability while casting a spell with improvise, that artifact won't be on the battlefield when you pay the spell's costs, so you won't be able to tap it for improvise.

Whir of Invention — ruling 7

Tapping an artifact won't cause its abilities to stop applying unless those abilities say so.

Whir of Invention — ruling 8

Equipment attached to a creature doesn't become tapped when that creature becomes tapped, and tapping that Equipment doesn't cause the creature to become tapped.

Whir of Invention : règles, fonctionnement et interactions (MTG)

Whir of Invention 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

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for .) Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.

Complete guide

Whir of Invention is a powerful blue instant that allows you to tutor an artifact directly onto the battlefield. By utilizing the Improvise mechanic, you can turn your non-creature treasures or utility equipment into the resources needed to find your winning piece.

Understanding Improvise

Improvise is a keyword that allows your artifacts to help pay for the generic mana portion of the spell's cost. For every artifact you tap after you have finished activating mana abilities, you reduce the total cost by {1}. It is important to remember that Improvise cannot pay for the three blue mana symbols in the cost; those must be paid using traditional mana sources.

Step-by-Step Resolution

When you cast Whir of Invention, you first choose a value for X. The total cost is then determined as {X}{U}{U}{U}. You then have the opportunity to activate mana abilities, and finally, you pay the cost by tapping artifacts for Improvise and spending mana. Upon resolution, you search your library for an artifact card with mana value X or less, put it onto the battlefield, and then shuffle your library.

Common Mistakes

A common error is trying to tap an artifact for both a mana ability and Improvise. If you tap an artifact like a Mana Vault for its own ability, it is already tapped and cannot be tapped again for Improvise. Additionally, remember that Improvise only applies while casting the spell; you cannot use it to pay for external costs like taxing effects from your opponent.

When to Play It

Because Whir of Invention is an instant, it is best used at the end of your opponent's turn or in response to a specific threat. This allows you to keep your mana and artifacts upright for defense until the last possible second, ensuring you find exactly the right tool for the current board state.

Interaction examples

Searching for a Solution

You choose X=0. The total cost is {U}{U}{U}. Even though X is 0, you still search your library and can put an artifact with mana value 0, such as a zero-cost utility artifact, onto the battlefield.

Handling Interruption

Counterspell

You cast Whir of Invention with X=4, tapping four artifacts to pay for the {X} cost and spending three blue mana. Your opponent casts Counterspell. Whir of Invention is moved to the graveyard from the stack, and you do not get to search your library or put anything onto the battlefield.

Drawing After a Denial

Arcane Denial

You cast Whir of Invention. An opponent responds with Arcane Denial. Whir of Invention is countered. At the beginning of the next turn's upkeep, you may draw up to two cards because your spell was countered by Arcane Denial, and your opponent will draw a card.

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

How it works : Whir of Invention

Original English text — Wizards of the Coast / Scryfall

#1February 9, 2017· Wizards of the Coast
Improvise doesn't change a spell's mana cost or mana value.
No other card is named in this ruling.
#2February 9, 2017· Wizards of the Coast
When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Improvise applies after the total cost is calculated.
No other card is named in this ruling.
#3February 9, 2017· Wizards of the Coast
Because improvise isn't an alternative cost, it can be used in conjunction with alternative costs.
No other card is named in this ruling.
#4February 9, 2017· Wizards of the Coast
Improvise can't pay for , , , , , or mana symbols in a spell's total cost.
No other card is named in this ruling.
#5February 9, 2017· Wizards of the Coast
Improvise can't be used to pay for anything other than the cost of casting the spell. For example, it can't be used during the resolution of an ability that says "Counter target spell unless its controller pays ."
No other card is named in this ruling.
#6February 9, 2017· Wizards of the Coast
If an artifact you control has a mana ability with in the cost, activating that ability while casting a spell with improvise will result in the artifact being tapped when you pay the spell's costs. You won't be able to tap it again for improvise. Similarly, if you sacrifice an artifact to activate a mana ability while casting a spell with improvise, that artifact won't be on the battlefield when you pay the spell's costs, so you won't be able to tap it for improvise.
No other card is named in this ruling.
#7February 9, 2017· Wizards of the Coast
Tapping an artifact won't cause its abilities to stop applying unless those abilities say so.
No other card is named in this ruling.
#8February 9, 2017· Wizards of the Coast
Equipment attached to a creature doesn't become tapped when that creature becomes tapped, and tapping that Equipment doesn't cause the creature to become tapped.
No other card is named in this ruling.
#9February 9, 2017· Wizards of the Coast
When using improvise to cast a spell with in its mana cost, first choose the value for X. That choice, plus any cost increases or decreases, will determine the spell's total cost. Then you can tap artifacts you control to help pay that cost. For example, if you cast Whir of Invention (a spell with improvise and mana cost ) and choose X to be 3, the total cost is . If you tap two artifacts, you'll have to pay .
No other card is named in this ruling.