Karn, the Great Creator — ruling 1

Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities are activated abilities and will have colons in their reminder text, such as equip. Triggered abilities (starting with "when," "whenever," or "at") are unaffected by Karn.

Karn, the Great Creator — ruling 2

Karn's first ability affects only artifacts on the battlefield. Activated abilities that work in other zones can still be activated.

Karn, the Great Creator — ruling 3

A noncreature permanent that turns into a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.

Karn, the Great Creator — ruling 4

If a permanent has {X} in its mana cost, X is considered to be 0.

Karn, the Great Creator — ruling 5

Karn's last ability can't get a face-down card in exile, even if you know it's an artifact card.

Karn, the Great Creator — ruling 6

In a casual game, a card you choose from outside the game comes from your personal collection. In a tournament event, a card you choose from outside the game must come from your sideboard. You may look at your sideboard at any time.

Karn, the Great Creator : règles, fonctionnement et interactions (MTG)

Karn, the Great Creator 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

Activated abilities of artifacts your opponents control can't be activated. +1: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value. −2: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.

Complete guide

Karn, the Great Creator is a powerful colorless planeswalker that dominates the board by locking down opponent resources and fetching tools from outside the game. As a master of artifice, Karn turns inanimate objects into living constructs while cutting off your enemy's ability to use their own mechanical tools.

The Static Lock and Animation

Karn's static ability is simple but devastating: opponents cannot activate abilities of artifacts they control. This includes mana abilities like those on mana rocks and utility abilities like equipment. His +1 ability allows you to turn a noncreature artifact into a creature until your next turn, with power and toughness equal to its mana value. If you target an opponent's noncreature artifact, they still won't be able to use its activated abilities, even after it becomes a creature.

Step-by-Step Resolution

When you use Karn's -2 ability, you first check your sideboard (in tournament play) or your collection (in casual play) for an artifact card, or choose a face-up artifact card you own in exile. You reveal the card and put it into your hand. Note that face-down exiled cards cannot be chosen. When using the +1 ability, the artifact remains a creature until the beginning of your next turn. If the artifact has an 'X' in its mana cost, its power and toughness will be 0 while it is a creature.

Common Mistakes

A common point of confusion is what constitutes an 'activated ability.' Karn only stops abilities formatted as '[Cost]: [Effect].' He does not stop triggered abilities, which start with 'When,' 'Whenever,' or 'At.' Additionally, Karn's static ability only affects artifacts on the battlefield; it does not stop cycling or other abilities that activate from the hand or graveyard. Finally, remember that if you animate an artifact that just entered the battlefield this turn, it will have 'summoning sickness' and cannot attack or use its own tap abilities.

When to Play Karn

Karn is best deployed when you need to shut down an opponent's mana production or search for a specific silver bullet from your sideboard. His ability to pull cards from exile also makes him an excellent counter to effects that remove your key artifacts from the game. He is particularly effective in decks that can protect him, allowing his static lock to persist over multiple turns.

Interaction examples

Animating The Aetherspark

The Aetherspark

You control The Aetherspark, which is an artifact. You activate Karn's +1 targeting it. Since The Aetherspark has no mana cost printed (mana value 0), it becomes a 0/0 creature and is immediately put into the graveyard unless you have an effect increasing its toughness. However, if it were already attached to a creature, it would remain attached until the animation effect is applied, at which point state-based actions would cause it to become unattached because creatures cannot be attached to other permanents.

Untapping with Tezzeret

Tezzeret, Cruel Captain

You use Karn's +1 to turn a noncreature artifact with mana value 4 into a 4/4 creature. You then activate Tezzeret, Cruel Captain's 0 ability targeting that artifact creature. Because it is currently an artifact creature due to Karn's effect, it untaps and receives a +1/+1 counter, making it a 5/5 until your next turn, at which point it reverts to being a noncreature artifact with a +1/+1 counter on it.

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

How it works : Karn, the Great Creator

Original English text — Wizards of the Coast / Scryfall

#1May 3, 2019· Wizards of the Coast
Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities are activated abilities and will have colons in their reminder text, such as equip. Triggered abilities (starting with "when," "whenever," or "at") are unaffected by Karn.
No other card is named in this ruling.
#2May 3, 2019· Wizards of the Coast
Karn's first ability affects only artifacts on the battlefield. Activated abilities that work in other zones can still be activated.
No other card is named in this ruling.
#3May 3, 2019· Wizards of the Coast
A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.
No other card is named in this ruling.
#4May 3, 2019· Wizards of the Coast
If a permanent has in its mana cost, X is considered to be 0.
No other card is named in this ruling.
#5May 3, 2019· Wizards of the Coast
Karn's last ability can't get a face-down card in exile, even if you know it's an artifact card.
No other card is named in this ruling.
#6May 3, 2019· Wizards of the Coast
In a casual game, a card you choose from outside the game comes from your personal collection. In a tournament event, a card you choose from outside the game must come from your sideboard. You may look at your sideboard at any time.
No other card is named in this ruling.