MTG Commander Deck Builder Agent Skill

Build a complete, balanced 100-card Magic the Gathering Commander (EDH) deck around a chosen commander. Use this skill whenever the user wants to build, brew, design, or upgrade a Commander/EDH deck, names a legendary creature and asks "build a deck around X", asks for a decklist for a commander,…

Context cost
22.2k tokensestimated from the bundle, loaded when it triggers
Bundle
11 files · 111.8 kB4 scripts among them — read before you run
Licence
MITthe author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Build a complete, balanced 100-card Magic the Gathering Commander (EDH) deck around a chosen commander. Use this skill whenever the user wants to build, brew, design, or upgrade a Commander/EDH deck, names a legendary creature and asks "build a deck around X", asks for a decklist for a commander, wants help picking cards that synergize with a commander, or wants a Commander deck within a budget or at a specific power bracket.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md33.6 kB · preview
--- name: mtg-edh-build ---
17# MTG Commander Deck Builder
18
19This skill builds a complete, well-tuned 100-card Commander deck around any commander the user
20chooses. It combines two things: **proven card data** (what real players actually run, from EDHREC
21via its JSON API, priced through Scryfall) and a **disciplined building methodology** that turns a
22pile of synergistic cards into a deck that actually functions — correct card-advantage density, enough
23ramp, enough interaction, the right land count, a sensible curve, and real win conditions.
24
25A deck is not a list of the 99 most powerful cards in a color. It is a machine where the parts reinforce
26each other. The whole job of this skill is to build that machine.
27
28**The build is grounded in comparable real decklists, and the budget is hit by reduction, not by starting
29cheap.** First pull the comparable proven lists for the commander and justify every inclusion by its
30presence/inclusion-rate there or a clear synergy reason. Then assemble a **solid reference deck for the
31target bracket *ignoring budget*** (allow a high ceiling — up to ~€1000 if that's what "solid" takes), and
32only then **budget down** by swapping expensive cards, most-expensive-first, for cheaper cards that fill the
33**same role/synergy**. If the budget can't be met while keeping the deck solid at the target bracket, say so
34and step down a bracket rather than shipping a deck weaker than it claims. Full detail in
35references/methodology.md — read it. Always report the deck's **actual** bracket (strictly determined per
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md5,134 words
Files11
LicenceMIT
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈300
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
21,925
on trigger
The instruction body and 10 supporting files, read only when the skill fires.
11.1%
of a 200k window
Ten skills this size would not fit in the window together.
050k100k150k200k context window

22.2k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

11 files, 111.8 kB on disk. Mostly text — the instructions the model reads — with 4 scripts in it that your client would run only if the instructions tell it to.

  • SKILL.md33.6 kB
  • references/brackets.md7.7 kB
  • references/data-sources.md5.8 kB
  • references/methodology.md16.6 kB
  • references/rating.md9.7 kB
  • references/scryfall-syntax.md7.3 kB
  • references/synergy.md8.2 kB
  • scripts/analyze_deck.py10.9 kB
  • scripts/edhrec_fetch.py4.3 kB
  • scripts/import_deck.py2.9 kB
  • scripts/scryfall_search.py4.8 kB
What is not in it

A skill installs nothing and depends on nothing: it is a folder your client reads. This one carries 4 scripts beside the text, so the bundle is 11 files you can review in full before installing. The MIT licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# MTG Commander Deck Builder · 22.2k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/mtg-commander-deck-builder/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/mtg-commander-deck-builder" ] && { [ ! -e .claude/skills/mtg-commander-deck-builder ] || { mv .claude/skills/mtg-commander-deck-builder "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/mtg-commander-deck-builder" .claude/skills/ && echo "Installed .claude/skills/mtg-commander-deck-builder"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add guuse/mtg-commander-deck-builder

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/mtg-commander-deck-builder/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/mtg-commander-deck-builder/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/mtg-commander-deck-builder" ] && { [ ! -e ~/.claude/skills/mtg-commander-deck-builder ] || { mv ~/.claude/skills/mtg-commander-deck-builder "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/mtg-commander-deck-builder" ~/.claude/skills/ && echo "Installed ~/.claude/skills/mtg-commander-deck-builder" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/mtg-commander-deck-builder/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. It appears as mtg-edh-build in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, mtg-commander-deck-builder.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referenceguuse/mtg-commander-deck-builder

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

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