Magic: The Gathering

The Arcane Labyrinth — Rules Reference (V6)

V6 Foreword and Changelog

Last updated 2025-12-30

2025-12-30 V6 Draft 1 Released

Version 6 of the Arcane Labyrinth ruleset aims to tweak and streamline the gameplay experience of the format. Various rules have been adjusted and tweaked for balance. Additional difficulity modifiers have also been added.

I. Overview & Objective

The Arcane Labyrinth is a high-stakes, solo "Dungeon Crawl" format for Magic: The Gathering. You control a single Hero (Avatar) and a deck of spells/creatures representing your party (the Vanguard).

• The Goal: Survive 100 rooms (cards) of an automated, escalating nightmare and defeat the Final Boss located at the bottom of the Labyrinth deck.
• The Enemy: The Labyrinth is an automated deck that plays itself. It follows strict behavioral rules to attack, cast spells, and grow in power.
• The Stakes: If your Hero’s Life hits 0, the game is over.

II. Deck Construction and Setup

1. The Hero (Avatar)

• Selection: Choose 1 Legendary Creature or Planeswalker. This is your Avatar.
• Start: It begins the game on the battlefield. It has no mana cost.
• Health: You have 20 Life. Damage to the player is damage to the Hero.
  • Note: Effects that target "Player Life" target Hero HP.

2. The Hero Deck (The Vanguard)

• Size: 60 Cards.
• Construction: Standard construction rules apply (max 4 copies of a card).
• Restriction: Maximum 1 Artifact card allowed in the main deck. (This encourages reliance on the Secret Shop).
• Banned: Cards with "You win the game" effects are disqualified 1.

3. The Secret Shop Deck

• Size: 10+ Artifact Cards.
• Role: Represents equipment and items you can buy during the run. This is considered an attribute of the Hero's kit, not the Labyrinth, and should synergize with the Hero’s deck.

4. The Labyrinth Deck (The Dungeon)

• Size: 100 Cards exactly.
• Composition:
  • Below card figures are guidelines. With the exception of the Mana color rules on the line below, and 5 legendary creatures, you are free to compose this deck however you’d like.
  • Lands: ~15 (Must include at least 1 Land for every color produced by the deck).
  • Creatures: 55–65.
  • Spells: 20–30.
  • Bosses: Must contain exactly 5 Legendary Creatures (or "Rare" equivalents if Legendaries are unavailable) distributed throughout the deck.
• The Final Boss: One specific Legendary Creature must be placed at the very bottom (card 100) of the deck.

III. Playing the Game

The Preparation Phase

Before the Labyrinth awakens, you have time to prepare your defenses.

1. Safe Turns: You receive 3 Safe Turns.
2. Actions: You may play lands, cast spells, and build your board state.
3. Restrictions:
   • You cannot conduct an Attack Phase (you cannot attack the Labyrinth directly).
   • You can use burn spells or mill effects to damage the Labyrinth deck.

The Dungeon Phase (The Game Loop)

Starting on Turn 4, the Labyrinth awakens.

1. The Labyrinth Draw Step

The Labyrinth reveals the Top 2 Cards of its library every turn. Resolve them sequentially:

• A. Lands:
  • Enter the battlefield, and immediately go to your land pool untapped. They can be used immediately.
  • Effect: Revealing a Land triggers the Shop Phase at the end of this Labyrinth turn, before the players turn.
• B. Creatures:
  • Enter with Haste.
  • Must Attack each turn if able (they never block).
• C. Spells & Traps:
  • Resolve immediately.
  • The Labyrinth ignores "Additional Costs" (e.g., sacrifice requirements are skipped unless mandatory for the effect to function) of a card.
  • Ambiguity Rule: If a card has multiple modes (e.g., "Choose one..."), roll a die to determine which effect is selected.
  • Targeting Rule: If a spell requires a target (e.g., "Destroy target permanent"), randomly determine the target among valid player permanents using a die roll.
• D. Global Enchantments/Artifacts:
  • Apply globally to the Labyrinth’s board until removed by the player.

The Labyrinth always plays at least 2 cards per turn. If a player effect prevents a draw/play, the Labyrinth ignores it or pushes through to ensure 2 cards enter play, unless the deck is empty. If the Labyrinth deck is empty and the final boss has been cleared, the player wins.

3. Labyrinth Interaction Rules (Keywords)

• Life Gain: If the Labyrinth would gain X life, instead shuffle X cards from the Labyrinth graveyard back into the Labyrinth deck.
  • Anti-Loop: If this happens >2 times to a single card, Exile that card instead.
• Dread/Manifest: Play the card face-down (2/2). Flip it face-up during the next Upkeep
• Deathtouch: If a Hero blocks a Deathtouch creature, the Hero is Exhausted.
• Return To Hand:
  • If the player plays a card with the effect of “Return target to hand” against the Labyrinth, the target goes to the Labyrinth’s graveyard. If the Labyrinth uses a “Return to hand” effect on itself, it goes to the top of the Labyrinth’s library.

Combat & Hero Mechanics

1. The Vanguard Priority System

Labyrinth creatures attack automatically using the following priority list:

1. The Wall: Creatures with Defender, Reach, or Vigilance are attacked first.
2. The Front Line: Your untapped creatures (Highest Power first).
3. The Avatar: If no eligible blockers remain, they attack the Hero directly.

This is slightly different from typical Magic, in that the Labyrinth can choose what creatures to attack, as opposed to just attacking and letting the player resolve. With that said, this is just a guideline for automating combat resolution. The player can, as in standard Magic, allocate specific creatures to specific attackers as part of blocking, and can choose to let the attack go straight to their hero.

2. Blocking with the Hero

Your Hero (Avatar) is a valid blocker.

• Successful Block: If Hero Toughness > Attacker Power, you take 0 damage to your Hero Health.
• Hero Exhaustion (The "Downed" State):
  • Trigger: If the Hero's Toughness is reduced to 0 or less (via combat damage or -X/-X effects), or if they block a Deathtouch creature, the Hero becomes Exhausted.
  • Effect:
    • The Hero is treated as Exiled until your next Upkeep.
    • Passive abilities cease to function.
    • They cannot block.
    • Any tokens, counters, or stateful effects on your hero are removed.
    • Crucial: You generally still take Hero Health damage from unblocked attackers while Exhausted. Eg you cannot Exile your hero in perpetuity to become invulnerable.
  • Recovery: At the start of your next Upkeep, return the Hero to the battlefield (Reset to base stats).

The Secret Shop

Trigger: If the Labyrinth played a Land this turn, the Shop opens at the End Step of the Labyrinth’s turn.

1. Reveal: Reveal the top 3 Artifacts from your Shop Deck.
2. Purchase: You may buy an artifact by sacrificing lands equal to its Mana Value.
   • Colored Costs: You must sacrifice lands capable of producing the required colors.
   • The item goes to your Hand (you must cast/equip it normally).
3. Scrap: Unpurchased cards go to the bottom of the Shop Deck.

Random Encounters

Every 3rd Turn (Turns 3, 6, 9...), roll a D20 before the Draw Phase27:

The Final Boss

When the bottom card (100th card) is reached:

1. Equipment: The Boss enters the battlefield equipped with the most expensive Artifact remaining in the Shop Deck (equipped for free).
2. Scaling Buffs:
   • If reached in < 10 Turns: Boss gets +10/+10.
   • If reached in < 15 Turns: Boss gets +5/+5).

IV: Optional Rules (Difficulty Mods)

These additional gameplay tweaks can make underwhelming Labyrinth decks pack a bit more of a punch. Additionally if your hero deck is a particularly good counter to a specific Labyrinth deck, these can help increase the challenge a bit.

• Entropy Draw (Scaling Difficulty): If the Player controls 10+ creatures OR a creature with Power 10+, the Labyrinth draws 3 cards per turn.
• Desperation Mode: If the Labyrinth deck has <50 data-preserve-html-node="true" cards remaining, all Labyrinth creatures gain Trample (prevents chump-blocking).