Prototype in MTG: Rules, FAQ, and Best Cards

Last updated on December 22, 2025

Arcane Proxy | Illustration by Kekai Kotaki

Who doesn’t love the idea of monstrous magic-imbued robots clashing on a war-strewn battlefield? Mech fans rejoice, there’s a Magic mechanic that embodies everything you love about the robot-on-robot clashes of properties like Transformers, Pacific Rim, and Gundam. And it’s got such a fitting name.

That’s right, this mechanic is The Brothers’ War’s prototype. I’ll be your resident robot-loving L1 judge here to answer any questions about how to cast your prototype creatures and how they behave in different game zones.

Ready? Let's get into it!

How Does Prototype Work?

Hulking Metamorph | Illustration by Diego Gisbert

Prototype is an additional option you have when casting a spell. You can cast a prototype creature for its normal casting cost in the top right of the card, or you can cast it for its prototype cost in the text box.

If you choose the prototype cost, the attributes of the card change. It has a different power, toughness, and mana cost, and the color of the card also changes. All other abilities remain the same regardless of which cost you choose to pay.

Here's the golden rule for understanding when you can and can’t use the prototype cost: If you aren’t casting the creature, prototype can’t be used.

Is Prototype an Activated Ability?

Prototype isn’t an activated ability but a static ability that provides a different possible casting cost for your creature. Pithing Needle, for example, won’t stop your opponent from casting a creature for its prototype cost.

Is Prototype an Alternate Cost?

Not precisely, because an alternate cost can still be applied to whichever prototype cost you choose. But functionally, it plays similarly to alternate casting costs just like evoke or blitz. You choose which set of characteristics the card has when you cast it. The prototype cost always results in less power and toughness, and a lower mana cost.

If a card allows you to cast a prototype spell “without paying its mana cost,” like Omniscience, for example, you can choose to cast the prototyped version of the spell for free, if for some reason you want the smaller version.

What's the Mana Value of a Prototyped Card on the Stack?

If you paid the prototype cost of a spell on the stack, that card has a mana value associated with the prototype cost. For example, if you cast Combat Thresher for its prototype cost then the spell will have a mana value of 3. Obviously, casting Thresher for its full cost gives it a mana value of 7.

What's the Mana Value of a Prototyped Card in Play?

The mana value of a prototyped card carries over once that permanent is in play. Paying the prototype cost of a card changes its physical mana cost, so you use that new mana cost to determine the mana value. If you paid to cast Phyrexian Fleshgorger and it resolves, the cost will remain on the battlefield, and the wurm will have a mana value of 3.

What Color Is a Prototyped Card in Play?

You can tell which color a prototype creature becomes by the mana symbols in its prototype cost. They’re always colorless cards in your hand but are treated as their new color if you pay the prototype cost.

If you pay to cast Skitterbeam Battalion, it’s a red spell on the stack and a red permanent in play.

I should mention the color identity of prototype cards as it relates to Commander. All prototype creatures are colorless by default, but their color identity includes their prototype colors. Arcane Proxy, for example, has a blue color identity and can only be played in blue Commander decks.

When You Prototype Is it an Artifact Spell?

The prototype reminder text says “it keeps its abilities and types,” meaning the artifact part of the card never changes. Prototype only exists on artifact creatures, and those spells remain artifacts whether their prototype cost was paid or not.

What Is the Color and Mana Value of a Prototype Card in the Graveyard?

Prototype cards in graveyards are colorless and have their normal mana values. Remember that golden rule: Prototype is irrelevant if you aren’t casting the card and it's not on the battlefield. If you’re just looking at the card's characteristics in another zone then you can ignore the prototype text.

Can You Prototype a Card if You Reanimate It?

Generally, no. Normal reanimation spells won’t allow you to pay the prototype cost for a card. Reanimation effects don’t generally ask you to cast the reanimation target, they just put the card from the graveyard onto the battlefield. If that’s the case then there’s no opportunity for you to pay an alternate casting cost like prototype.

Can You Prototype if You Cast from the Graveyard?

If a spell or ability lets you specifically cast a creature from a graveyard, you can choose to cast it for its prototype cost. Even if you're casting it without paying its mana cost, you can choose to cast it for its prototype cost.

For example, the effect on Rivaz of the Claw allows you to cast Fallaji Dragon Engine from your graveyard for either its normal cost or its prototype cost. Same goes for a card like Wondrous Crucible.

What Happens If You Blink a Prototype?

When you blink a prototype creature it re-enters the battlefield with all its normal non-prototype characteristics. Even if you paid the prototype cost the first time you cast it, blinking it “resets” everything and you’re left with the bigger colorless version of the card.

What's the Point of Prototype?

Prototype exists to flesh out the themes of The Brothers’ War. The set revolves around the conflict between Urza and Mishra, who both command armies of machines to wage war against each other. These prototype creatures represent the destructive robotic forces of that war.

From a design standpoint, prototype is a great way to reward players for playing ramp strategies with giant game-ending threats. They provide mana sinks for the Powerstone token producing cards in BRO while having a cheaper alternate cost that makes them more tenable for Limited.

Is Prototype Good?

There's nothing wrong with prototype, but it has not proven to be a standout mechanic. Mechanics that offer flexibility usually see play somewhere, even if that means you only see these cards in Commander. Some creatures like Steel Seraph and Phyrexian Fleshgorger have seen a small amount of Standard play.

Unfortunately, many of the prototype creatures in BRO Limited were overshadowed by the relatively fast speed of the format.

Gallery and List of Prototype Cards

There are 21 prototype creatures in Magic, 17 from the main The Brothers' War set, two from Alchemy: The Brothers' War, one from Modern Horizons 3, and another from the supplementary Jumpstart set for BRO.

• Rootwire Amalgam
• Autonomous Assembler
• Arcane Proxy
• Skitterbeam Battalion
• Steel Seraph
• Spotter Thopter
• Hulking Metamorph
• Iron-Craw Crusher
• Phyrexian Fleshgorger
• Fallaji Dragon Engine
• Combat Thresher
• Rust Goliath
• Depth Charge Colossus
• Woodcaller Automaton
• Goring Warplow
• Blitz Automaton
• Boulderbranch Golem
• Cradle Clearcutter
• Frogmyr Enforcer
• Warzone Duplicator
• Forgefire Automaton

Best Prototype Cards

The recursion at no extra cost makes Forgefire Automaton ripe for value in sacrifice engines. There are plenty of cards that weren't designed to have 3 power, much less 8, but Forgefire will give it to them anyway. If you were confused about prototype cards at first, don't be, this one is simply powerful and worth a mythic wildcard.

The Warzone Duplicator lets you play with your opponent's cards in a fair way. Non-Alchemy players get a taste of this card in the Arena Cube from time to time.

Arcane Proxy didn't really stick in Standard, but there's still potential here. It mimics the effects of cards like Snapcaster Mage and Torrential Gearhulk, which were powerhouses in the past.

Phyrexian Fleshgorger did see some Standard play, mostly as a sideboard option against aggro decks. It plays the role of an aggressive 3-drop very well and also makes for a powerful reanimation or blink target.

Autonomous Assembler and Steel Seraph have decent stats and abilities regardless of which mode they're on, with the Seraph having a short stint in Standard.

Rootwire Amalgam can also make a big token. Like, big. Sometimes that’s enough to see play with the right supporting pieces.

Decklist: Prototype in Pioneer

Phyrexian Fleshgorger | Illustration by Steve Prescott

This is a pretty tame deck that was meant to serve as a prototype for a casual deck based on the mechanic. Some of the cards have since rotated from Standard (remember when Reckoner Bankbuster was legal?), with the prototype creatures on their way out soon enough, so consider this a mild Pioneer deck.

There's a bit of a cute idea here, with the deck attempting to play prototype creatures for cheap, then either blink them or recur them with Fake Your Own Death to plop them back into play on their fully upgraded side. Planar Incision has some janky combo potential with Arcane Proxy.

Wrap Up

Woodcaller Automaton | Illustration by Ryan Pancoast

Even though prototype didn't end up being a meta-defining mechanic, or even a standout mechanic in its own Limited format, there’s no denying that casting giant robots and war-mechs is Magic at its most exciting.

The printing of Frogmyr Enforcer let us know that prototype's still in the designers' back pockets if they ever wanted to use it again, though that card was too clever not to make, so maybe it wasn't an indication of prototype coming back any time soon.

Have you tried prototype in Magic? Got any burning questions I didn’t cover here? Let me know in the comments or over on the Draftsim Discord.