creating-commander-decks

name: creating-commander-decks description: This skill should be used when the user asks to "build a Commander deck", "create an EDH deck", "make a deck for [commander name]", "fill out a partial decklist", "add a deck to the collection", or mentions building a new Commander/EDH deck from a commander name. version: 1.0.0

Creating Commander Decks

Overview

End-to-end workflow for building a Commander deck from a commander name to finished, validated files. Produces a deck JSON and companion README in decks/.

When to Use

• User names a commander and wants a deck built
• User has a partial card list and wants it completed
• User wants to add a new deck to the decks/ collection

Workflow

digraph deck_flow {
    rankdir=TB;
    node [shape=box];

    start [label="User provides commander name" shape=doublecircle];
    validate [label="1. Validate commander\n(Scryfall API)"];
    research [label="2. Research on EDHREC\n(popular cards, themes, combos)"];
    identity [label="3. Define deck identity\n(theme, bracket, budget)"];
    build [label="4. Build card list\n(fill all categories)"];
    bracket_check [label="5. Validate bracket compliance"];
    bracket_ok [label="Bracket rules pass?" shape=diamond];
    fix [label="Swap offending cards"];
    prices [label="6. Fetch prices\n(prices.py / Scryfall)"];
    budget_ok [label="Within budget?" shape=diamond];
    swap [label="Find cheaper alternatives"];
    json [label="7. Write deck JSON"];
    readme [label="8. Write deck README"];
    verify [label="9. Verify everything"];
    done [label="Done" shape=doublecircle];

    start -> validate -> research -> identity -> build -> bracket_check;
    bracket_check -> bracket_ok;
    bracket_ok -> prices [label="yes"];
    bracket_ok -> fix [label="no"];
    fix -> bracket_check;
    prices -> budget_ok;
    budget_ok -> json [label="yes or no budget"];
    budget_ok -> swap [label="over budget"];
    swap -> prices;
    json -> readme -> verify -> done;
}

Step 1: Validate Commander

Query Scryfall: GET https://api.scryfall.com/cards/named?exact={name}

Extract: name, colors, color_identity, mana_cost, type_line, oracle_text. Confirm the card is a legal commander (legendary creature or has "can be your commander").

Step 2: Research on EDHREC

Fetch the commander's EDHREC page for:

• High synergy cards and staples for the color identity
• Common themes/archetypes
• Typical combo lines
• Average deck composition

Use this as a starting point, not a copy-paste. The user's theme and bracket filter what's appropriate.

Step 3: Define Deck Identity

Confirm with the user:

• Theme: one-sentence concept (e.g., "dwarves tap for Treasures to tutor artifacts and dragons")
• Target bracket (1-5): constrains card quality, combos, Game Changers
• Card count: 100 standard, 112 for MPC.com printing
• Budget: optional ceiling; skip if user doesn't mention it

Step 4: Build Card List

Fill categories to hit roughly these counts (for 100-card deck):

Categories used in JSON: commander, creature, planeswalker, sorcery, instant, enchantment, artifact, land.

Step 5: Validate Bracket Compliance

Cross-reference the card list against bracket rules. For the full bracket rule table and Game Changers list, consult references/bracket-rules.md.

Flag Rule 0 considerations: cards that are technically legal for the bracket but may draw table discussion (e.g., From the Ashes as soft mass LD in bracket 3, Blood Moon changing land types).

Step 6: Fetch Prices

Run the bundled pricing script:

python3 ${CLAUDE_PLUGIN_ROOT}/scripts/prices.py {deck-slug}

Or use Scryfall API directly. Summarize: total cost, top 10 expensive cards, cost by category. If user set a budget, identify cards to swap for cheaper alternatives.

Scryfall rate limit: 50-100ms between requests. Use User-Agent: MTGDeckTracker/1.0. On macOS, use SSL context with /etc/ssl/cert.pem.

Step 7: Write Deck JSON

File: decks/{commander-slug}.json

For the full JSON schema and color identity reference, consult references/deck-format.md.

Group cards by category in the array. Basics use their total quantity (e.g., "quantity": 24 for Mountains).

Step 8: Write Deck README

File: decks/{commander-slug}.md

Structure:

# Commander Name
**Color Identity:** {identity} | **Bracket:** {n} ({name}) | **Cards:** {count}

## Theme
One or two sentences.

## How It Plays
Short paragraph on core game plan.

## Key Cards
5-8 cards with brief notes on why they matter.

## Bracket Notes
Game Changers count, Rule 0 flags.

## Card Breakdown
Table with category counts.

## Decklist

### Commander (1)
1x Commander Name

### Creatures (28)
1x Card Name
1x Card Name

### Instants (10)
1x Card Name
...

### Lands (36)
1x Card Name
14x Mountain

Each category header includes the total card count for that category. Cards listed as {quantity}x {name}. Categories appear in this order: Commander, Creatures, Planeswalkers, Sorceries, Instants, Enchantments, Artifacts, Lands. Empty categories are omitted.

Step 9: Verify

• Sum of all card quantities matches card_count
• Category counts in README match actual JSON data
• Decklist in README lists every card from the JSON with correct quantities
• Bracket notes accurately reflect Game Changers count
• All card names are real (validated against Scryfall)
• Commander slug in filename matches JSON content

Common Mistakes

• Miscounting lands: basics have high quantity values — don't count them as 1
• Game Changers misidentification: always check the official list; many strong cards (Sol Ring, Exploration, Scapeshift) are NOT Game Changers
• Forgetting Rule 0 flags: cards like Blood Moon or From the Ashes are bracket-legal but worth noting
• Wrong color identity names: it's "Gruul" not "Red/Green" in the JSON field

Additional Resources

Reference Files

• references/bracket-rules.md — Full bracket rule table, Game Changers list, and compliance checking guide
• references/deck-format.md — Complete JSON schema, color identity names, and example deck structure

Scripts

• ${CLAUDE_PLUGIN_ROOT}/scripts/prices.py — Fetch card prices from Scryfall API for a deck or all decks