Commander Format Rules

Understand the rules and restrictions of Commander (EDH) format and how Icarian validates your decks.

Commander Format Overview

Commander (also called EDH - Elder Dragon Highlander) is a multiplayer Magic format with unique deck building rules:

100-card deck (including commander)
Singleton (only 1 copy of each card, except basic lands)
Color identity (all cards must match commander’s colors)
Legendary commander (must be a legendary creature or planeswalker with “can be your commander”)

The 100-Card Rule

Your deck must contain exactly 100 cards:

1-2 commanders (in command zone, not counted in the 99)
99 other cards (main deck)

Icarian validates this automatically: - Shows current card count - Highlights when count is incorrect - Prevents adding beyond 100 cards

Example: - 1 commander + 99 cards = ✓ Valid - 2 partner commanders + 98 cards = ✓ Valid - 1 commander + 100 cards = ✗ Invalid (too many)

Color Identity

All cards in your deck must match your commander’s color identity.

What Is Color Identity?

A card’s color identity includes: - Mana symbols in the casting cost - Mana symbols in rules text - Color indicator (on transform cards) - Characteristic-defining abilities that define color

Example - Atraxa, Praetors’ Voice: - Mana cost: {W}{U}{B}{G} - Color identity: White, Blue, Black, Green - Valid cards: Any card with ONLY these colors or colorless - Invalid cards: Red cards, or any card with red mana symbols

Color Identity Validation

Icarian checks every card in your deck: - ✓ Cards matching commander’s color identity are allowed - ✗ Cards with colors outside the identity are flagged as errors

Example Violations: - Adding a red card to a white/blue commander - Adding a card with {R} in its rules text (like Caged Sun set to red)

Partner Commanders and Color Identity

When using partner commanders, their color identities combine:

Example: - Commander 1: Thrasios (Green/Blue) - Commander 2: Tymna (White/Black) - Combined Identity: White, Blue, Black, Green - You can now use cards from all four colors!

Singleton Rule

You can only include 1 copy of each card (except basic lands).

Basic Lands Exception

You can include unlimited copies of basic lands: - Plains - Island - Swamp - Mountain - Forest - Wastes

Note: Snow-covered basics are also unlimited.

Non-Basic Lands

All non-basic lands follow the singleton rule: - Only 1 Command Tower - Only 1 Reliquary Tower - Only 1 of each dual land

Icarian flags duplicates: - Scans your deck for duplicate cards - Shows error if duplicates are found (except basic lands)

Commander Eligibility

Only specific cards can be your commander:

Legendary Creatures

Most commanders are legendary creatures: - Any legendary creature can be your commander - Most legendary creatures are valid choices

Planeswalkers

Some planeswalkers can be commanders: - Must have rules text stating “can be your commander” - Examples: Aminatou, Estrid, Rowan Kenrith

Background Commanders

Some creatures can have a Background as a second commander: - Must have “Choose a Background” ability - Pair with an enchantment with “Background” type

Partner Commanders

Some legendary creatures and planeswalkers can partner to serve as dual commanders:

Partner (Generic): Can pair with any other commander that has “Partner” - Examples: Thrasios + Tymna, Kraum + Vial Smasher - When you select a generic Partner commander, you can choose any other generic Partner as the second commander - Cards with “Partner with [Specific Card]” cannot be paired with generic Partner commanders

Partner With [Specific Card]: Can only pair with the specific named partner - Examples: Will Kenrith + Rowan Kenrith, Pir + Toothy, Gorm + Virtus - These commanders are designed as specific pairs - When you select one, Icarian will automatically filter the second commander search to show only the valid partner - You cannot pair these with generic Partner commanders

Friends Forever: Can pair with any other “Friends Forever” commander - Stranger Things commanders - Similar to generic Partner, but for a specific set of commanders

Icarian validates partner pairings automatically: - Uses MTG JSON leadershipSkills.commander data - Enforces “Partner with” restrictions by filtering search results - Flags invalid commander selections - Prevents pairing generic Partner commanders with “Partner with” specific commanders

Format Legality

All cards in your deck must be Commander-legal.

Banned Cards

Some cards are banned in Commander: - Black Lotus - Ancestral Recall - Time Walk - Others (see official Commander ban list)

Icarian checks legality: - Uses MTG JSON legalities.commander data - Flags banned cards as errors - Updates automatically when ban list changes

Silver-Bordered Cards

Silver-bordered cards (from Un-sets) are generally not legal in Commander, except during special events or with playgroup approval.

Ante Cards

Cards with “ante” mechanics are banned in all formats, including Commander.

Deck Validation Panel

Icarian’s validation panel shows all rule violations:

Error Types

Card Count - Deck has too many or too few cards
Color Identity - Card violates commander’s color identity
Singleton - Duplicate cards found (excluding basic lands)
Banned Cards - Card is banned in Commander format
Commander Eligibility - Selected commander cannot be a commander

Error Severity

Error (Red) - Rule violation, deck is illegal
Warning (Yellow) - Potential issue, but deck is legal

Fix all errors before playing!

Advanced Rules

Hybrid Mana

Cards with hybrid mana count both colors in color identity.

Example: Deathrite Shaman {B/G} - Color identity: Black AND Green - Cannot be used in mono-black or mono-green decks - Can be used in Golgari (B/G) or higher color decks

Phyrexian Mana

Cards with Phyrexian mana symbols count that color in identity.

Example: Dismember {1}{B/P}{B/P} - Color identity: Black (even though you can pay with life) - Cannot be used in colorless or non-black decks

Transform Cards

Double-faced cards include the color identity of both faces.

Example: Arlinn Kord / Arlinn, Embraced by the Moon - Front: Red/Green - Back: Red/Green - Color identity: Red and Green

Reminder Text

Color symbols in reminder text (parenthetical italics) DO NOT count toward color identity.

Example: Caged Sun - Rules text mentions choosing a color - Reminder text shows mana symbols, but they’re in reminder text - Color identity: Colorless

Commander Damage

While Icarian validates deck construction, it doesn’t track commander damage during games:

Each commander deals separate commander damage
21 combat damage from a single commander is lethal
Track this manually during gameplay

House Rules

Many playgroups use house rules that modify Commander rules:

Allowing certain banned cards
Changing starting life total
“Rule 0” conversations about power level

Icarian validates against official Commander rules. Adjust for house rules manually.