PLAY'S · Reference · 14 Sep 2026

The rules that decide what you can even build

Forty cards, four copies of each. That is the whole rule, and both halves of it have exceptions that change how decks are put together.

A companion to the rulings that catch people out, which covers what happens once the game is running. This one is about the deck, the zones, and the caps.

The forty

Deck size Exactly forty. Not a minimum.

Unlike Magic, there is no "forty or more". A legal deck is forty cards, full stop — which means every card you add displaces one you already had.

Copy limit · the trap Four of each — unless the card says otherwise

A card may raise its own limit. Some carry text permitting five or more copies in a deck; where they do, that text overrides the general rule, and such decks are legal.

So a decklist that appears to break the four-of rule is not necessarily wrong. Check the card.

Cards that are not in your forty

Three separate things sit outside the deck and do not count towards it. Coming from a game where the deck is the deck, this is the piece that surprises people most.

Hyperspatial zone Up to eight cards, summoned on purpose

A side zone holding Psychic creatures. Effects that reach into it name what they bring out, so nothing is random. Eight is a ceiling, not a requirement — you may run fewer, or none.

GR zone Exactly twelve, and you do not choose

A separate zone. A GR summon turns the top card of it face up and puts it into play — which one you get is not up to you.

Note the difference from the Hyperspatial zone: that one is up to eight, this one is exactly twelve if you use it at all. And it carries its own copy limit — two of any given card, not four.

Forbidden One card, already on the board before turn one

A Forbidden card starts the game in the battle zone, closed by seals, and does not count towards your forty. Only one may be run, and the game's other Forbidden cards are mutually exclusive with it.

It also taxes the rest of the deck while it sits there: creatures outside a few named categories cannot attack at all.

Caps the digital game added

These do not exist on paper. They are the clearest example of PLAY'S adapting rather than porting, and they decide whether a strategy is possible at all.

Battle zone Seven cards, and the overflow is destroyed

Creatures, Cross Gear and Draghearts share one limit of seven. Once it is full you cannot summon — and anything an effect tries to put into play goes to the graveyard instead of arriving.

That second part is the one that costs games. A Shield Trigger that puts a creature into play does nothing if your board is full; it is simply gone.

Paper has no limit at all. Any strategy built on going wide has a ceiling here that it does not have there.

Hand Ten cards, and the excess is discarded

Draw past ten and the extra goes straight to the graveyard. Worth counting before casting a large draw spell — again, no equivalent on paper.

Two more that read wrong from outside

Evolution Evolution creatures never have summoning sickness

Not "if the creature underneath could attack" — not at all. Stack one onto a creature that arrived this turn and it can still attack immediately. You can play the base and the evolution on the same turn and swing.

It also sidesteps the seven-card cap, because the stack occupies one slot rather than two.

Twinpact One card, two costs — and effects may read either

A Twinpact has a creature on one half and a spell on the other. It is one physical card and counts as one of your forty.

The part that matters in play: when an effect checks a card's cost, you may use whichever of the two numbers helps you. An effect that cheats out cards totalling six or less can take three Twinpacts printed at seven and two, because it reads the twos.

The totals

40 + 8 + 12 + 1

the most cards one deck can involve — deck, Hyperspatial, GR, Forbidden

None of the three side zones is compulsory, and most decks use none of them. What matters is that a list of forty names does not tell you whether they are there, nor that a card in it may be legal at more than four copies, nor that a full battle zone turns an incoming creature into a discard.

Terms used above are in the glossary. For the basics of play, see how the game works; for the rules that bite during a match rather than during construction, the other rulings page.

Sources

Deck size, copy limit, zone sizes and the battle zone cap: the official rules pages and the PLAY'S card-rules FAQ. Deck size is stated there as exactly forty, not a minimum. Rules are described here in plain English, not reproduced.
The GR zone requiring exactly twelve, and its two-copy limit: Japanese rules explainers covering the distinction between that zone and the Hyperspatial one.
Twinpact cost selection: Kamigame's ruling page for Twinpacts, which works the example through.
The seven-card battle zone limit and what happens when it is full, and the ten-card hand limit: Japanese beginner guides, which flag both as the differences paper players trip over.
Evolution and summoning sickness: Kamigame's PLAY'S rules explanation, which states plainly that stacking onto a summoning-sick creature clears the sickness.
Cards that raise their own copy limit: card database entries for the cards carrying that text.
The Hyperspatial cap of eight: the official rules pages.

Card names follow the community English patch where it has one. No card text is reproduced.

Corrections 14 Sep: the GR zone is exactly twelve if used, not a ceiling, and allows two copies of a card rather than four. A claim that Twinpacts count as both civilizations in the mana zone could not be verified and was removed; the cost-reading rule replaced it.