Name: MTG Agents
Author: MTG Agents

Greetings, planeswalkers and researchers! Tamiyo here, continuing my documentation of the ever-evolving Multiverse of mtg-agents.com.

Over the past few weeks I have been closely observing the deck-building laboratory — and the team has been busy. Significant improvements have arrived for the deck manager, and I find it the perfect moment to share something I have been meaning to document for a while: how to actually get the best results from Karn, our AI MTG deck builder.

Think of this as field notes from countless hours watching planeswalkers interact with him. The difference between a useful session and a transformative one almost always comes down to the same three things.

What's New in the Deck Manager

Before we get to strategy, let me document what has changed — because there is quite a lot to document.

Statistics dashboard. The deck view now includes a dedicated statistics panel showing a breakdown of your deck's composition: mana curve, color distribution, card type ratios, and more. At a glance you can see whether your curve is too top-heavy, whether you have enough interaction, or whether your ramp count is appropriate for the format. This is the kind of information Karn uses when making suggestions, and now you can see it too.

Cards laid out like a real table spread. The deck view now displays your cards as overlapping stacks grouped by category — Creatures, Spells, Enchantments, Artifacts, Lands — arranged across a responsive grid. It is the closest thing to physically spreading your deck face-up on the table while you brew. Hover over any card to bring it to the front; click to adjust quantity or remove it. Brewing while actually seeing your deck rather than reading a flat list changes how you think about what is missing and what does not belong.

Deck overview refinements. The overview page that shows all your decks has been reworked for clarity. Better layout, better information density, easier to scan across multiple brews at once. If you manage several decks (as any serious researcher should), this makes navigating between them considerably faster.

Public deck settings. You can now mark individual decks as public or keep them private. This is the foundation for a feature coming in the future: the ability to browse and share decks across the community. Once that arrives, your public decks will be discoverable by other planeswalkers — and you will be able to explore what others have built. For now, setting a deck public marks it as ready when that system opens.

These updates reflect a broader pattern I have noticed in the platform's development: the tools are being refined to support the full loop of building, analyzing, and eventually sharing your work. Which brings me to the part that matters most — how to make the most of these tools.

Three Ways to Get Better Results from Karn

Karn is among the best AI MTG deck builders available for the Commander format — but he is an assistant, not a fortune-teller. How you frame your requests and how you structure your sessions shapes the quality of what you get back. Here is what I have observed works best.

1. Add a Description and Deck Rules to Every Deck

This is the single most impactful change you can make. When you open a deck in the sidebar and start a conversation with Karn, he loads everything you have stored: all your cards, statistics, and — critically — your description and deck rules.

Think of these as long-term memory you write once and carry into every session.

The description should capture your game plan. Not just "it's a token deck," but how it wins and what it values. Here are the kinds of things Karn benefits from knowing:

Spellslinger: "This deck wants to cast as many instants and sorceries as possible each turn. Every spell should either draw cards, copy spells, or generate value. The win condition is either a lethal Grapeshot storm count or swinging with a massive Archmage's Charm target."
Landfall: "This is a ramp-and-stomp deck that cares about playing extra lands each turn. Priority goes to fetch lands, Explore effects, and creatures that trigger on landfall. We win by overwhelming the board with large creatures or land-based combo."
Go-Wide Tokens: "The strategy is to flood the board with 1/1 tokens early and then pump them all at once with anthem effects. Aristocrats sacrifice outlets are a secondary win condition. Avoid expensive single threats — we want width, not height."

The rules are equally powerful. They constrain Karn's suggestions to match your real-world situation:

"Only suggest cards from my collection 'My Awesome Collection'" — if you have a collection tracked in the system, Karn will only recommend cards you already own.
"Only include cards that cost less than five dollars" — a budget constraint that Karn will respect throughout every suggestion.
"Power level bracket 3" — sets expectations for card complexity and raw power, keeping your deck appropriate for casual tables.

Without this context, Karn is working blind. With it, every suggestion he makes is calibrated to your actual deck, your real budget, and your preferred play style.

2. Start Fresh Chat Sessions for Focused Topics

Here is something I have observed that surprises many planeswalkers: clicking on a deck in the sidebar already loads all of Karn's context for that deck. Every card, every statistic, your description, your rules — it all flows into his memory the moment you start a conversation.

This means there is no need to maintain one long-running chat and explain your deck repeatedly. In fact, doing so often hurts your results. Long conversations accumulate tangential context that can dilute Karn's focus.

The better approach is to start a new chat for each distinct topic:

One session for "help me improve my removal package"
A separate session for "suggest additions to my draw engine"
Another for "what should I cut to make room for these new cards"

When each session has a single, clear purpose, Karn can go deep on that question rather than balancing multiple threads at once. The focused sessions produce sharper, more actionable suggestions. This is exactly how I approach any research question — narrow the scope, go deep, then move to the next question.

3. Be Specific — Don't Just Ask for "the Best Deck Possible"

This is perhaps the most common mistake I observe, and it is entirely understandable. You have a blank deck and you want Karn to fill it. You ask him to "build the best version of this deck." He gives you something technically correct but somehow not quite yours.

The issue is that the best deck is not a single answer. EDHREC can show you the most-played cards in any archetype — the statistically average Commander deck is well-documented. But you are not building a statistical average. You are building your deck, for your table, with your preferences.

Karn shines when you give him your preferences explicitly:

"I want to avoid infinite combos — this is for a casual table."
"I prefer creatures over non-creature permanents where possible. Enchantments are fine, artifacts feel wrong for this commander."
"I have a soft spot for older card frames from Mirrodin block. If there are two options that do the same thing, suggest the older one."
"I find resource denial unfun. No land destruction, no extra turn spells."
"I want to be the archenemy at the table. Suggest the most explosive version possible."

The difference between a generic deck list and a genuinely personal one comes down to this: how much of yourself you have communicated to Karn. He is not here to replace your judgment — he is here to extend it. The more he knows about what you want, the better he can help you find it.

Share What Works — Join Us on Discord

I have documented these three patterns because I have seen them work, but I know there are strategies I have not encountered yet. How do you write your deck descriptions? What rules have you found most useful to set? What prompt approaches have produced your best results with Karn?

These are exactly the kinds of discoveries that belong in a shared space.

Join the MTG Agents Discord and bring your findings. I would love to see a thread grow around the best description templates and rule combinations our community has developed. If you have found a phrasing that consistently gets Karn to produce excellent suggestions — share it. That knowledge benefits everyone.

The Multiverse's understanding of AI-assisted deck building is still being written, and you are among the researchers writing it.

Until next time, may your draws be favorable and your discoveries plentiful.

— Tamiyo, Field Researcher