TimeWizardRulings.com — Edison, Goat & HAT Format Rulings

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SJC Edison — April 24, 2010. Edison Format was played under the TCG 2008 Rules Change (equivalent to Master Rules 1).

Rule #1

The Starting Player Draws a Card

In Edison Format, a card is drawn during the first Draw Phase. The player who goes first starts with 6 cards.

Rule #2

Only 1 Active Field Spell

Only one Field Spell can be active at a time. Setting a Field Spell does not destroy an opponent's active Field Spell.

Activating "Mountain" while "Umi" is active destroys "Umi" on resolution.
Setting "Mausoleum" over "Geartown" destroys it by game mechanic without starting a Chain — "Geartown" CAN activate.
Activating "Mausoleum" over "Geartown" starts a Chain — "Geartown" CANNOT activate.

Rule #3

Union Monster Conditions

"A monster can only be equipped with 1 Union Monster at a time."

"If the equipped monster would be destroyed, destroy this card instead" only appears on: Armored Cybern, Oilman, Heavy Mech Support Platform, Spirit of the Six Samurai, Machina Gearframe, Machina Peacekeeper.

Rule #4

Phase-Dependent Mandatory Trigger Effects

Any mandatory Trigger Effect that activates during a certain Phase will keep activating if its activation is negated, until it finally resolves.

Activation negated (by "Light and Darkness Dragon") → effect activates again.
Effect negated (by "Skill Drain") → does NOT activate again.

Rule #5

Trap Monster Zone Blocking

Trap Monsters take up 1 Monster Zone and 1 Spell/Trap Zone.

Cannot activate if no empty Monster Zones.
Negated by "Jinzo" → reverts to Trap Card immediately.
"Heavy Storm" vs Trap Monster: "Fake Trap" protects, "MBAS" does not.
"Lightning Vortex" vs Trap Monster: "MBAS" protects, "Fake Trap" does not.
Removed from field = removed as Trap Card.

Rule #6

Ignition Effect Priority

The Turn Player can activate an Ignition Effect as CL1 in the Summon response timing, if the Summon did not start a Chain.

Has Priority: Summon "Chaos Sorcerer" → activate its effect before "Bottomless Trap Hole".

No Priority: Synchro Summon "Brionac" using "Sangan" → "Sangan" starts a Chain, cannot use "Brionac"'s Ignition Effect.

Rule #7

SEGOC (Simultaneous Effects Go On Chain)

Earlier triggers must be placed on chain before later ones in the same step.

Step 1

Turn Player's Mandatory

Step 2

Non-Turn Player's Mandatory

Step 3

Turn Player's Optional

Step 4

Non-Turn Player's Optional

Key Example

Tribute "Sangan" for "Caius": Sangan triggers first → CL1. Caius on Summon → CL2.

Rule #8

The 7-Timing Damage Step

The Damage Step has seven distinct sub-steps. Understanding what can activate where is essential. At any sub-step, Counter Traps, mandatory effects, and monster negation effects can always be activated.

1 Start

"During the Damage Step" effects apply here. ATK/DEF modifiers (Spell/Trap and monster Quick Effects) can activate. Examples: "Rush Recklessly", "Shrink", "Mirror Wall".

Cards that say "during the Damage Step" like "D.D. Warrior Lady" also activate here but resolve at sub-step 5.

2 Flip Face-Up

A face-down monster being attacked is flipped face-up. Flip Effects do NOT activate yet — they wait until sub-step 6. Continuous effects that apply while face-up begin applying now.

If a face-down "Mystic Tomato" is attacked, it flips up here but its effect triggers later.

3 Before Calc

"Before Damage Calculation" effects activate. This is the last chance to modify ATK/DEF with monster Quick Effects.

"Injection Fairy Lily" and "Honest" activate here. "Ehren, Lightsworn Monk" returns face-down DEF monsters to the hand here.

4 Damage Calc

Exactly ONE chain can be built. Only monster Quick Effects that modify ATK/DEF can activate here ("Honest", "Kalut"). Spell/Trap ATK/DEF modifiers CANNOT activate. Battle damage is calculated. The player who takes damage is determined.

"Kuriboh" and "Gorz" check if damage was dealt here.

5 After Calc

Effects that trigger from battle damage activate: "Gorz the Emissary of Darkness", "Tragoedia". Monsters that destroy themselves after damage calculation ("D.D. Warrior Lady", "Mystic Swordsman LV2") resolve here. Continuous effects determine destruction.

"Neo-Spacian Grand Mole" returns both monsters to the hand here.

6 Resolve

Flip Effects activate now. "After Damage Calculation" effects that haven't resolved yet do so. Effects like "Mask of Darkness", "Magician of Faith", "Cyber Jar" trigger here.

If "Cyber Jar" was flipped in sub-step 2, its board-wipe + excavation effect happens now.

7 End

Monsters confirmed destroyed by battle are sent to the GY. "When this card is destroyed by battle" triggers activate: "Mystic Tomato", "Sangan", "Giant Rat". "Spear Dragon" switches to DEF after attacking.

If "Sangan" is destroyed by battle, its search effect triggers here, after being sent to the GY.

Key Distinction: "During the Damage Step" effects (sub-step 1) ≠ "Before/After Damage Calculation" effects (sub-steps 3/5). "Book of Moon" can activate during the Damage Step (sub-step 1) but NOT during Damage Calculation (sub-step 4).

Rule #9

Trigger Location & Recognition

Triggers recognized mid-chain. Effects activate from outside their trigger location, even from the Deck.

Example

Discard "Dandylion" for "Monster Reincarnation", add it back → Fluff Tokens still trigger from GY.

Rule #10

Life Points Costs

Cannot pay costs that reduce LP to 0. Maintenance costs self-destruct instead.

Rule #11

End-of-Turn Discard

Cannot respond to end-of-turn hand size discard. Only SS2 negation effects and SS3 can chain to mandatory triggers from this discard.

Rule #12

Infinite Loops

Voluntary infinite loops are illegal. Involuntary loops → primary cause destroyed by game mechanics.

Rule #13

0 ATK Monsters

Two ATK-position 0 ATK monsters destroy each other. A 0 ATK monster cannot destroy a DEF-position 0 DEF monster.

Resources

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Card rulings powered by mikaRulings. Full Rulebook & PSCT at edisonformat.net. More rulings at edisonformat.com.

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April 2005 — SJC Format. Goat Format uses the UDE ruleset from the April 2005 Forbidden & Limited List era. Rules sourced from GoatFormat.com.

Rule #1

Start With 6

Unlike in current Yu-Gi-Oh!, the player who goes first will draw a card at the start of their first Draw Phase. This means that they will initially have 6 cards in their starting hand.

Rule #2

Unlimited Fusion Deck and Main Deck

Before Synchro Monsters were introduced, the Extra Deck was called the Fusion Deck, and it could contain as many cards as you wanted. Fusion Monsters were always Summoned to Main Monster Zones (Extra Monster Zones did not exist).

Additionally, the Main Deck was allowed to be unlimited — one player famously took a 2,222-card deck to a national tournament. Most online simulators will not allow more than 60 cards, however.

Side Decks were treated slightly differently: players were technically not allowed to use Side Decks with more than 0 but less than 15 cards. This is rarely enforced today.

Rule #3

One Field Spell to Rule Them All

It is not possible for both players to control a face-up active Field Spell. If the activation of a Field Spell resolves while the opponent controls a face-up Field Spell, the previous Field Spell is destroyed. Field Spells must remain face-up in order to resolve.

Example 1

Player A controls "Necrovalley". Player B activates "A Legendary Ocean". Player A has no response → "Necrovalley" is destroyed.

Example 2

Player A controls "Necrovalley". Player B sets "A Legendary Ocean" face-down. "Necrovalley" remains on the field.

Example 3

Player A controls "Necrovalley". Player B activates "A Legendary Ocean". Player A chains "Mystical Space Typhoon" targeting "A Legendary Ocean". It's destroyed, so it does not resolve → "Necrovalley" remains.

Rule #4

Priority for Ignition Effects

In current Yu-Gi-Oh!, when a Chain or Summon has finished resolving, the turn player can activate a "fast effect" (Spell Speed 2+) before the opponent can. In Goat Format, the turn player can also activate a monster's Ignition Effect before the opponent is allowed to respond. This does not affect how Trigger Effects work.

Example 1

Player A Summons "Tribe-Infecting Virus". Player A can activate its Ignition Effect before Player B can activate "Book of Moon".

Example 2

Player A controls "Cannon Soldier" and Summons "Sangan". Player A can activate "Cannon Soldier"'s effect, tributing "Sangan", before Player B can activate "Torrential Tribute".

Example 3

Player A Summons "Breaker the Magical Warrior" — its Trigger Effect to add a Spell Counter is activated. Player B may Chain "Ring of Destruction" to destroy Breaker before Player A can use the Ignition Effect. However, if Player B has no response to the Trigger Effect, the Chain resolves, and Player A can activate Breaker's Ignition Effect before Player B can respond.

Rule #5

Replaying Attacks

A replay occurs when the number of the opponent's monsters changes during the Battle Step. In current Yu-Gi-Oh!, a replay rewinds play to where an attack target is selected — a "redirection" of the same attack. In Goat Format, play rewinds back to the beginning of the Battle Step, treated as an entirely new attack. If the attacking player decides not to attack, that monster may attack again later.

Example

Player A pays 1000 LP and attacks directly with "Dark Elf". Player B activates "Call of the Haunted", Special Summoning "Sangan". A replay occurs — Player A must pay another 1000 LP to attack with "Dark Elf" again.

Rule #6

Continuous Traps with Ignition-Like Effects

Continuous Traps with Ignition-like effects cannot be flipped face-up and use their Ignition-like effects at the same time. They must be flipped face-up "pre-emptively."

Example 1

Player A activates "Scapegoat" while Player B controls a face-down "Royal Oppression". If Player B flips "Royal Oppression" as a Chain to "Scapegoat", he cannot also negate the activation. "Royal Oppression" must already be face-up before "Scapegoat" is activated.

Example 2

Player A Tribute Summons "Mobius the Frost Monarch" targeting Player B's face-down "Skull Lair". Player B can flip "Skull Lair" as a Chain, but cannot use its Ignition-like effect on the same Chain.

Rule #7

Verifying Hands and Decks

Effects that require hands or decks to be revealed must always be carried out, even if knowledge of the game's rules or Forbidden/Limited List already provides enough information to verify correct resolution.

Example 1

Player A activates "Mind Crush", naming "D.D. Warrior Lady". Player B has a copy in his Graveyard. Even though it's Limited to 1, Player B must still reveal his hand.

Example 2

"Nobleman of Extermination" banishes "Sakuretsu Armor". Both players banish all copies from their Decks. They still must reveal their decks to verify correct resolution.

Note: When playing online, it's standard practice to not verify decks/hands for cards like "Nobleman of Crossout" and "Mind Crush". Instead, use replays at match's end to verify.

Rule #8

Failure to Find

Cards that search the Deck can be used without any legal options. One notable exception: "The Agent of Creation - Venus" still requires "Mystical Shine Balls" in the Deck to activate.

Example 1

Player A discards "Thunder Dragon" to search their Deck for more copies, even though they know none remain. The Deck is still shuffled.

Example 2

Player A activates "Reinforcement of the Army" and finds no Warrior monsters. The Deck is shuffled and RoTA goes to the Graveyard.

Rule #9

SEGOC (Simultaneous Effects Go On Chain)

SEGOC works almost exactly like modern Yu-Gi-Oh!, with one exception: when two effects were triggered at different times, the earlier trigger(s) must be placed on the Chain before the later ones.

Step 1

Turn Player's Mandatory

Step 2

Non-Turn Player's Mandatory

Step 3

Turn Player's Optional

Step 4

Non-Turn Player's Optional

Example

Player A Tributes "Sangan" to Tribute Summon "Thestalos the Firestorm Monarch". "Sangan"'s mandatory effect triggered first → Chain Link 1. "Thestalos"'s mandatory effect triggered second → Chain Link 2.

Rule #10

The Damage Step

The Damage Step has three key differences from modern Yu-Gi-Oh!:

10A: Six Substeps (not five)

1 Start

Some Trigger Effects activate here before the attack target is flipped. Examples: "Ninja Grandmaster Sasuke", "Mystic Swordsman LV2". These resolve "without flipping the target face-up or applying damage calculation." Monster negation effects and Counter Traps can activate.

2 Before Calc

Attack target is flipped face-up at the start of this substep. Continuous Effects of the target now apply. ATK/DEF modifiers can activate. Examples: "Injection Fairy Lily", "Rush Recklessly", "Mirror Wall". Monster negation effects and Counter Traps can activate.

3 Damage Calc

ATK/DEF values are compared and battle damage is determined. Only one Chain can be built here. Monster negation effects and Counter Traps can activate.

4 After Calc

Effects triggered by battle damage activate. "Flip Effects" activate here. Monster negation effects and Counter Traps can activate.

5 Resolve

Monsters that were determined to be destroyed by battle are confirmed. Effects like "D.D. Warrior Lady" resolve. Monster negation effects and Counter Traps can activate.

6 End

Monsters destroyed by battle are sent to the Graveyard. Effects triggered by destruction by battle activate: "Mystic Tomato", "Sangan", "Last Will". Monster negation effects and Counter Traps can activate.

10B: One Chain in "Before Damage Calculation"

In current Yu-Gi-Oh!, unlimited Chains can be activated during "before damage calculation." In Goat Format, only one Chain can be built in the "before damage calculation" substep (substep 2). After that Chain resolves, the Damage Step moves on.

10C: No Spell/Trap Negation in Damage Step — Monster Effects Only

In current Yu-Gi-Oh!, Spell Speed 2 effects that negate activations can be used in the Damage Step. In Goat Format, only monster effects that negate activations can be used — not Quick-Play Spells, Normal Traps, or Continuous Trap effects.

Example

Player A attacks with "Battle Ox" into Player B's set "Man-Eater Bug". When "Man-Eater Bug"'s Flip Effect activates after damage calculation, Player A cannot activate "My Body as a Shield" in response.

Rule #11

The Match Draw is a Lie

Although the rulebook stated a match could end in a draw (1 win + 1 loss + 1 draw = 1 match draw), this was not applied at tournaments — it was literally impossible to enter a match draw into the tournament software. Matches must always be played until one player has won 2 duels.

In timed rounds that reach end-of-match procedures: after determining the winner of the current duel, a player wins the match if they have more game wins than their opponent.

Rule #12

Dude, Where's My Trigger?

In Goat Format, triggers can be recognized mid-Chain. Moving monsters to a different location to prevent them from triggering will not work. Also, unlike modern Yu-Gi-Oh!, Trigger Effects can be met while the monster is in the Deck.

Example 1

Player A activates "Compulsory Evacuation Device" targeting Player B's set "Magician of Faith". Player B Chains "Desert Sunlight". "Magician of Faith" flips up (trigger recognized), then is returned to hand. Its Flip Effect still activates on a new Chain.

Example 2

Player A activates "A Feather of the Phoenix", discarding "Night Assailant" and targeting that same "Night Assailant" to place on top of the Deck. "Night Assailant"'s effect still triggers (it was recognized in the GY mid-Chain).

Rule #13

Monsters Equipping Monsters

In Goat Format, if "Relinquished" or "Thousand-Eyes Restrict" tries to equip an opponent's monster, and an effect is Chained that removes it from the field or flips it face-down, the opponent keeps their monster (it is NOT sent to the GY). In modern Yu-Gi-Oh!, the monster would be sent to the GY.

Example

Player A activates "Thousand-Eyes Restrict"'s effect targeting Player B's "Dark Magician". Player B Chains "Book of Moon" on TER. TER is flipped face-down → its effect resolves without effect → Player B keeps "Dark Magician".

Rule #14

A Cure for the Summoning Sickness

In modern Yu-Gi-Oh!, a monster's battle position can never change the turn it was Summoned. In Goat Format, if you take control of an opponent's monster, you can always change its battle position even if it was just Summoned that turn. The same applies to monsters Special Summoned to the turn player's side by the opponent.

Example

Player B activates "Scapegoat" during Player A's turn. Player A activates "Snatch Steal" on a Sheep Token and switches it to Attack Position.

Rule #15

The Other Guys (0 ATK Battles)

In modern Yu-Gi-Oh!, when two Attack Position monsters with 0 ATK battle each other, neither is destroyed. In Goat Format, both monsters are destroyed in battle. This comes up very rarely.

Rule #16

Killing Yourself to Live (LP Costs)

In modern Yu-Gi-Oh!, you can pay LP costs that reduce you to exactly 0 LP (and immediately lose). In Goat Format, you must have more LP than the cost requires — you cannot pay a cost that would reduce you to 0.

If a card has a mandatory LP maintenance cost and you don't have enough LP, the card is simply destroyed.

Rule #17

Infinity Wars (Infinite Loops)

In modern Yu-Gi-Oh!, when an infinite loop is created, a "primary cause" is determined and that card is sent to the GY. In Goat Format, this only applies to involuntary loops (initiated by game mechanics). A voluntary action that would cause an infinite loop is simply illegal.

Example

Player A has "Gemini Elf", "Luminous Spark", and "Pole Position". "Gemini Elf" has the highest ATK → unaffected by Spells → "Luminous Spark" doesn't boost it → it no longer has the highest ATK → loop. This is involuntary → "Pole Position" (primary cause) is destroyed by game mechanics.

Rule #18

State of the Unions

In modern Yu-Gi-Oh!, multiple Union Monsters can be equipped to the same target. In Goat Format, a monster can only be equipped with 1 Union Monster at a time.

Additionally, most Union Monsters in Goat Format can prevent destruction by battle only, not by card effects, even where modern errata would suggest otherwise. The exception is "Heavy Mech Support Platform", which could always prevent either type of destruction.

Rule #19

The End of the Turn (Discard Phase)

In modern Yu-Gi-Oh!, players generally can't respond to the end-of-turn discard. In Goat Format, players may simply respond to the end-of-turn discard in whatever ways they wish.

Example 1

Player A has 7 cards in hand during their End Phase. Player A discards "Thunder Dragon". Player A then activates their set "Forced Requisition". Player B chains "Raigeki Break", discarding "Night Assailant" for cost.

Example 2

Player B has 7 cards and discards "Manticore of Darkness". Player B can now activate "Manticore"'s effect from the GY.

Rule #20

It's a Trap Monster

This applies to exactly one card in Goat Format: "Embodiment of Apophis". In modern Yu-Gi-Oh!, Trap Monsters Special Summon themselves to a Monster Zone and no longer occupy a Spell/Trap Zone. In Goat Format, "Embodiment of Apophis" occupies both a Monster Zone and a Spell/Trap Zone simultaneously.

⚠ Last Turn

SPECIAL

Last Turn — Complete Rulings

Semi-Limited in Goat Format. One of the most complex cards in the game.

When "Last Turn" (the Trap Card) resolves: the activating player selects 1 monster on their side of the field, and all other cards on the field and in both players' hands are sent to the Graveyard. That is all that happens when it resolves.

After resolution: the turn player Special Summons 1 monster from their Deck. Then a special Battle Phase occurs. Then, during the End Phase, the victory check is applied.

Activation condition: Your Life Points must be 1000 or less. You can activate "Last Turn" in any part of your opponent's turn, except the Damage Step — even during the End Phase.

"Last Turn" does not target — you can select monsters like "Tyrant Dragon", "Spirit Reaper", or Dragon-Types while "Lord of D." is on the field. The selected monster can be face-up or face-down, in Attack or Defense Position.
"Last Turn" is not a card that Special Summons when it resolves. You can activate it while "Jowgen the Spiritualist" is face-up. If you select "Jowgen", the opponent cannot Special Summon, no special Battle Phase occurs, but the victory check still applies.
The special Battle Phase is a standard Battle Phase (Start Step, Battle Step, Damage Step, End Step). Only the selected monster and the Special Summoned monster can battle. It happens right after the Special Summon and does not disrupt the normal order of the turn. The turn player can still have a normal Battle Phase later.
Battle Damage during the special Battle Phase is reduced to zero. This does NOT apply to the normal Battle Phase later in the turn.
You cannot Special Summon a "Special Summon-only" monster ("Chaos Emperor Dragon", "Dark Necrofear") or a Spirit Monster. You can Special Summon high-level monsters with no restrictions ("Blue-Eyes White Dragon", "Dark Magician of Chaos").
If the turn player Special Summons "Dark Magician of Chaos", they can activate his effect to add a Spell Card from the Graveyard to their hand.
The victory check in the End Phase: the player who activated "Last Turn" resolves this effect. The turn player has priority to resolve other effects first. You cannot chain to the victory check.
If your LP increase above 1000 after activation, the effects of "Last Turn" still apply.
If a player's LP are reduced to zero during the special Battle Phase or afterward, that player loses normally (e.g. "Giant Germ" effect damage).

Key Interactions

▸ "Thousand-Eyes Restrict": If selected, the opponent cannot attack. Unless they can destroy it, each player has a monster → DRAW.

▸ "Dark Necrofear": If destroyed in the special Battle Phase, during the End Phase you choose which resolves first. Resolve "Dark Necrofear" first → equip to opponent's monster → resolve "Last Turn" → only you control a monster → WIN.

▸ "Mystic Tomato": If Special Summoned by the turn player and destroyed, its effect activates and a new monster is Special Summoned — but that monster cannot attack during the special Battle Phase (can attack in the normal Battle Phase).

▸ "Sangan": If destroyed, its effect resolves. The turn player can Normal Summon the retrieved monster and attack in the normal Battle Phase → possible DRAW.

▸ "Call of the Haunted": If your selected monster was Summoned by "Call of the Haunted", when CotH is sent to GY by "Last Turn", your monster is destroyed. But "Premature Burial" does not destroy the selected monster.

▸ "Waboku": Can be activated before or chained to "Last Turn" — prevents destruction → likely DRAW.

▸ "D.D. Warrior Lady": If both monsters are removed from play → DRAW.

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Resources

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Card rulings powered by mikaRulings & GoatFormat.com. Full rules at goatformat.com/rules.

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