What is the Prototype mechanic in Magic: The Gathering?

Prototype is a keyword ability on artifact and artifact creature cards that lets you cast them in two ways: for their full colourless mana cost with their normal power and toughness, or for a smaller coloured mana cost with reduced power and toughness. The card has a special two-part frame showing both sets of characteristics. It was introduced in The Brothers' War (2022).

Does casting a card with its Prototype cost count as casting it with an alternative cost?

No. The prototype cost is treated as the spell's base mana cost, not an alternative cost. This means effects that let you cast a spell without paying its mana cost (like Omniscience) can still apply even if you intended to cast the prototyped version.

What happens to a Prototype card when it goes to the graveyard?

In every zone except the stack and battlefield, a prototype card reverts to its normal (default) characteristics — the large, colourless version. So if a creature you cast as a prototyped spell dies, it sits in the graveyard as its full, normal self. Reanimating it would bring back the full version.

Does Prototype affect a card's colour identity for Commander?

Yes. Even though the card's default mana cost is entirely colourless, the coloured mana symbols in the prototype cost are part of the card's colour identity. A card with a {2}{G} prototype cost has green in its colour identity and requires a Commander that includes green.

What happens if a Prototype spell is copied on the stack?

The copy is also treated as a prototyped spell. It uses the alternative (prototype) power, toughness, and mana cost, not the card's normal characteristics. Any rule or effect that refers to a prototyped spell applies to the copy as well.

What sets have Prototype cards?

Prototype was introduced in The Brothers' War (BRO, November 2022) and also appeared in Alchemy: The Brothers' War. It returned in Modern Horizons 3 (MH3, June 2024), making those cards legal in Modern.

Prototype: The MTG Mechanic Explained

There's something deeply satisfying about a card that grows with your mana. Prototype is exactly that kind of design: a single artifact card that you can deploy early as a modest, coloured creature, or hold back and cast as its true, enormous self when you have the mana to match. It first appeared in The Brothers' War (BRO, 2022), and it's one of the most elegant expressions of artifact-creature identity the game has seen in years.

What is Prototype?

Prototype is a keyword ability that lets you cast an artifact or artifact creature card in two different ways - for its full (and often hefty) default cost, or for a smaller, coloured alternative cost that also changes the creature's power and toughness.

Every prototype card has a special two-part card frame. The main frame shows the card's normal mana cost, power, and toughness. Inset below the type line is a smaller frame containing the Prototype ability with its alternative mana cost and a reduced power/toughness. When you cast the card, you choose which version you want. Pay the prototype cost and you get the smaller, coloured creature. Pay the full cost and you get the big, colourless original.

The key insight: this isn't really a discount or an alternative cost in the rules sense. Whichever cost you choose is simply treated as that spell's base mana cost at that moment. This matters more than it might seem at first glance.

How Prototype rules work

The rules here are worth understanding carefully, because Prototype interacts with some common effects in non-obvious ways.

Choosing which version to cast

When you cast a prototype card, you choose at that moment whether to cast it normally or as a prototyped spell (CR 718.3). There's no going back once you've made that choice - the decision happens while casting.

While a prototyped spell is on the stack, or once it resolves onto the battlefield, it uses only its alternative power, toughness, and mana cost. The normal characteristics are completely replaced (CR 718.3b).

Colour identity

Here's an important one for Commander players. Prototype cards have a default mana cost that is entirely colourless. In the normal zones - your hand, graveyard, exile, library - a prototype card is colourless. But if the prototype cost includes coloured mana symbols, the spell and the permanent it becomes are also that colour or colours while on the stack and battlefield (CR 718.3b).

This means the card's colour identity for Commander deck-building purposes does include the colours from the prototype cost.

Copying prototyped spells

If someone copies a prototyped spell on the stack, the copy is also a prototyped spell - it uses the alternative characteristics, not the card's normal ones (CR 718.3c). The same applies if a permanent that was cast as a prototyped spell gets copied on the battlefield (CR 718.3d).

Back in other zones

Once a prototype card leaves the stack or battlefield - say, it dies and goes to the graveyard - it reverts to its normal characteristics (CR 718.4). The "prototyped" state only exists while it's a spell or a permanent on the battlefield. In your hand, it's the big colourless version again.

What stays the same

Everything on the card other than power, toughness, and mana cost remains the same regardless of which mode you chose (CR 718.5). The abilities, card types, subtypes, name - all identical between modes.

Rules note: The prototype reminder text refers to the creature's "size" as shorthand for its power and toughness together. This shorthand is unique to Prototype among keyword reminder texts - it's made possible by the special inset frame that shows both numbers visually, so spelling them out separately in the reminder text wasn't necessary.

Common misunderstandings

Prototype is not an alternative cost. Effects that let you "cast a spell without paying its mana cost" (like Fierce Guardianship effects or Omniscience) can still apply on top of a prototyped casting - because the prototype cost is simply the spell's base mana cost in that case, not an alternative cost layered on top.
The card's normal characteristics don't disappear permanently. It reverts in every zone except the stack and battlefield.
Copiable values include the alternative characteristics. If something copies the card as a copiable value while it's prototyped, it copies the prototyped version (CR 718.2a).

Strategy: playing with and against Prototype

The core tension

Prototype cards force you into a real decision every time you cast them. Do you need a creature now, even at reduced size? Or is it worth waiting to deploy the full version later?

This tension is the mechanic's greatest strength from a gameplay perspective. A prototype card is never dead in your hand - it's always potentially castable at some point in the game, which makes them unusually flexible curve pieces for artifact-heavy strategies.

Early deployment vs. late power

Casting a prototype card early gives you a coloured creature that can contribute to the board while you develop your mana. The tradeoff is that the full version often has significantly more power, toughness, or additional abilities that make the wait worthwhile.

In general, the prototyped (smaller) version is usually a fair deal for its cost - competitive enough to play on curve, not embarrassing in the late game if you've already cast it. Think of it like getting a solid creature now versus a potentially game-breaking one later.

Deck-building considerations

Prototype leans green and blue. The coloured prototype costs skew toward {G} and {U}, which means these cards fit most naturally into artifact-focused decks in those colours.
Commander loves this mechanic. The flexibility of never having a completely stranded high-cost card is enormously valuable in a longer game with variable mana development. Prototype cards rarely feel like a dead draw.
Cost reduction synergies. Because prototype cards have a default colourless cost that's typically 5 or more, they pair naturally with effects that reduce the cost of artifacts or colourless spells.
Reanimation targets. A prototype card in your graveyard has its normal (large) characteristics. Reanimating it brings back the full version - potentially ahead of schedule.

Playing against Prototype

The main thing to account for is the flexibility. You can't always predict which version your opponent will cast, which makes the timing of your interaction more complicated. A removal spell held for the "big" creature might have to answer a smaller one earlier, or vice versa.

Countering a prototyped spell counters the spell, obviously - but the card still exists with its full characteristics in the graveyard afterward.

Notable Prototype cards

The card pool with Prototype is relatively focused, introduced in BRO and expanded in Modern Horizons 3 (MH3, 2024). Here are a few standouts that illustrate why the mechanic works so well.

Haywire Mite - A tiny green prototype creature at its smaller cost, this card punched well above its weight class because of what it does, not how big it is. A targeted way to exile enchantments or artifacts that also provides a reasonable body.

Blightsteel Colossus is the kind of card that makes you understand why Prototype was designed the way it was - enormously powerful at its full cost, and the mechanic's design space is built around that fantasy of getting something smaller early and something massive late.

Within the BRO set specifically, prototype creatures ranged from aggressive early drops in their prototyped forms to battlefield-dominating creatures at full cost. The mechanic was designed so both modes felt like real choices rather than one being clearly correct in all situations.

History of Prototype

Prototype debuted in The Brothers' War (November 2022), a set centred on the ancient war between Urza and Mishra and their competing armies of artifacts and constructs. Thematically, the mechanic is a perfect fit: a prototype is literally an early, smaller version of something that will eventually be built to its full, intended scale. The idea of deploying a war machine in a reduced form while you gather resources to complete it captures the set's flavour exactly.

The mechanic was subsequently included in Alchemy: The Brothers' War, the digital-first extension of BRO on MTG Arena.

Prototype made a return appearance in Modern Horizons 3** (MH3, June 2024), bringing the mechanic to Modern-legal cards for the first time and demonstrating that Wizards sees it as a mechanic with ongoing potential rather than a one-set curiosity.

As of the most recent Comprehensive Rules update (November 14, 2025 - Edge of Eternities), Prototype is codified under CR 702.160 and CR 718.