Implement Rulebreaker (+Partial implementation of DeckRule)

[BigCrunch22]

Rulebreaker mechanic + partial DeckRule deckbuilding framework

Summary

This adds a new custom keyword, Rulebreaker, and the engine infrastructure needed to support it: a partial implementation of the DeckRule: line-type framework sketched in #8066 ("Rework deckbuilding rules into a set of objects"). Rulebreaker cards bend specific deckbuilding restrictions (color identity, deck size) when they're your commander. All 12 cards in the Rulebreaker cycle are implemented and scripted, and Adventure Mode's separate, pre-existing deck-legality enforcement has been checked against them and patched where it wasn't DeckRule-aware.

Background

Rulebreaker cards read like:

Rulebreaker — A deck with this commander can have artifact creature and Equipment cards of any color identity and any basic land cards.

This is a deckbuilding-legality effect, not a live-game one — it changes which cards are legal to put in the deck, not anything that happens once a game starts.

#8066 already proposes the right shape for this: a new top-level script line, DeckRule:, parsed independently of K: lines, with rule classes like ColorIdentity and Size. This PR implements that framework — scoped to what Rulebreaker actually needs (ColorIdentity and Size), not the issue's full vision (Copies, Commander, FormatPool, Variants, FormatRestrictions are not attempted here).

New: the DeckRule framework (forge-core)

Three new classes in forge.deck, plus a new shared restriction-matching helper in forge.card:

• DeckRule — abstract base and dispatcher. Parses DeckRule:<RuleClass>:<Key$ Value | ...> lines and handles ActiveSection$ gating (e.g. a rule can be scoped to apply only while its card is the actual Commander). parseAll(PaperCard) also picks up that specific card's own marked colors (see AllowedAdditionalColor$ below), so a rule built from a deck's actual commander copy already knows the player's choice; parseAll(Iterable<String>) is the raw-line overload for callers like the live game Card that only have a card face's raw data, not a full PaperCard.
• DeckRuleColorIdentity — DeckRule:ColorIdentity:.... Supports:
  • Exempt$ <branches> — exempts matching cards from the color-identity check entirely. Branches are comma-separated (OR); within a branch, tokens are dot-then-plus, mirroring how ValidCard$/Card.isValid() restriction strings already work elsewhere in the engine. Recognized tokens: real core/super/subtype words (via CardType.parse), the bare word Permanent, or a stat filter (powerGE4, cmcGE7, ...). The actual parsing/matching for this now lives in CardRulesPredicates.restrictionList() (see below) rather than in this class.
  • Disable$ True — waives the color-identity check entirely (e.g. a Paradise Bird-style card).
  • AllowedAdditionalColor$ <n> + AllowedAdditionalColorType$ <branches> — grants a budget of n extra colors (beyond the commander's own color identity) to cards matching the AllowedAdditionalColorType$ branch grammar. Rather than auto-detecting which extra color(s) the player wants as cards get added, the player picks them upfront on the commander itself (Cryptic Spires-style) via a new deck-editor menu item — see Mobile UI below. This reuses the engine's existing PaperCard.getMarkedColors()/copyWithMarkedColors() mechanism, the same one Cryptic Spires-style lands already use, instead of inventing new state-tracking.
• DeckRuleSize — DeckRule:Size:AdjustMax$ <Unlimited|±n>. Only AdjustMax$ is implemented; AdjustMin$/Cumulative$ are left alone since Advantageous Proclamation already has its own hardcoded check in DeckFormat, and wiring an overlapping rule risked double-applying the adjustment.
• CardRulesPredicates.restrictionList() (new, in the existing forge.card package) — the generalized branch-list parser (dot-then-plus tokenizing, type/supertype/subtype matching via CardType.parse, the Permanent keyword, and a power/toughness/cmc stat-filter shorthand) that both Exempt$ and AllowedAdditionalColorType$ are built on. Pulled out of DeckRuleColorIdentity into a shared, general-purpose predicate per review feedback. It's also Changeling-aware, so a Changeling correctly satisfies any creature-type branch (e.g. Exempt$ Angel,Basic.Land) instead of being missed.

Engine plumbing changes

forge-core

• ICardRawAbilites.java / CardFace.java — new deckRules bucket + getDeckRules(), mirroring the existing keywords bucket exactly (including the functional-variant copy-down logic).
• CardRules.java — Reader.parseLine() gets a DeckRule case (alongside the existing D: cases for DeckHints/DeckNeeds/etc.); new getDeckRules() accessor.
• DeckFormat.java:
  • getDeckConformanceProblem() — gathers each commander's active DeckRuleColorIdentity/DeckRuleSize rules once, then consults them in both the main-deck and sideboard color-identity loops, and applies Size adjustments before the deck-size check.
  • isLegalCardForCommanderPredicate(commanders) — the predicate that actually controls which cards a live deck-editor UI shows in its catalog. Since a commander's AllowedAdditionalColor$ pick now lives on its own marked colors instead of being inferred from the rest of the deck, this only needs the commander list — no priming from the deck's current contents.

forge-game

• Player.java — new getStartingLibrarySize(), computed directly as getRegisteredPlayer().getDeck().getMain().countAll() rather than tracked as a separate field with its own setter.
• AbilityUtils.java — exposes it as Count$YourStartingLibrarySize, in both places YourStartingLife is already handled.
• Card.java — getAbilityText(CardState state), the method that actually composes a card's live displayed text, now folds each active DeckRule's Description$ in right after the keyword-reminder text, matching where the Oracle template places it. Previously nothing carried a card's DeckRule: lines from forge-core over to the live game Card at all, so a Rulebreaker's description only ever showed up in its static, manually-duplicated Oracle: text — visible in out-of-game previews (deck editor, card database) but never on an actual permanent, in hand, or in the command zone. This runs through the same view-update path every card already relies on for its keyword/trigger/static text (updateStateForView() → updateKeywords() → updateAbilityText()), so it's populated reliably from the moment a card is created, with no extra per-zone plumbing needed. Because this lives in forge-game, it's shared by every GUI (desktop included) rather than being another mobile-only patch.

Mobile UI (forge-gui-mobile)

FDeckEditor.java needed several fixes to actually reflect DeckRule in the deck editor's live catalog (Android and iOS share this file via forge-gui-mobile, so one fix covers all three; forge-gui-desktop was checked and doesn't need equivalent changes — see Desktop below):

• canOnlyBePartnerCommander() — was doing its own raw hasNoColorsExcept() check with zero DeckRule awareness, wrongly gating the "Add to deck" menu item for legitimately-exempt cards. Now consults each active DeckRuleColorIdentity rule directly (allowsOffColorIdentity, approvesAdditionalColor) before falling back to that check.
• CatalogPage.refresh() — this is what actually controls catalog visibility (via cardPool.retainIf(...)), a different and more consequential gate than the menu-item check above. It calls DeckFormat.isLegalCardForCommanderPredicate(), which is now DeckRule-aware the same way.
• New "Allowed Additional Colors" menu item, added to addPerCardItems() — shown on a commander card only while it has an active AllowedAdditionalColor$ budget (hasAllowedAdditionalColorBudget()). Mirrors the existing "Color Identity" menu item Cryptic Spires-style lands already use: it opens a color picker (capped at the rule's getAdditionalColorCount(), excluding colors already in the commander's identity), replaces the commander with a copy carrying the chosen colors via copyWithMarkedColors(), and refreshes the catalog page so it immediately reflects the new choice.

Desktop (forge-gui-desktop)

No changes needed. Desktop's Commander editor doesn't do live catalog filtering at all — its own class doc comment says "least restrictive mode; all cards are available," and Main/Sideboard always show the fully unfiltered pool regardless of commander. It only enforces color identity at match-start time via GameLobby.java calling DeckFormat.getDeckConformanceProblem(), which is already DeckRule-aware through the forge-core changes above.

Adventure Mode (forge-gui-mobile)

Per review: Adventure Mode does have its own deck-legality enforcement, separate from everything above, and it wasn't DeckRule-aware. DuelScene.java's pre-battle deck fixup (applyAdventureDeckRules/applyAdventureCommandZoneRules) runs right before every duel — Adventure can't just block you from starting a fight with an "illegal" deck the way GameLobby can, so instead it silently rewrites the deck to fit. Two concrete breaks for Rulebreaker:

• Color identity — its filter only understood raw commander color identity plus the pre-existing wildcard-color mechanic (getAddsWildCardColor()); with no Exempt$/Disable$/AllowedAdditionalColor$ awareness, it would silently strip a Rulebreaker's legitimately-exempt off-color cards (e.g. The Everforger's off-color artifact creatures/Equipment) out of the deck before every duel.
• Deck size — its max-deck-size cap came straight from format.getMainRange().getMaximum(), with no DeckRuleSize awareness, so Whtz, the Bibliophile's AdjustMax$ Unlimited deck would get randomly trimmed back down to 99 cards before every fight.

Fixed by reusing the existing logic rather than re-deriving it: DeckFormat.allowsOffColorIdentity()/approvesAdditionalColor() were widened from private to public static so DuelScene can call them directly, and a small applyCommanderSizeRule() helper mirrors DeckFormat's own Unlimited/AdjustMax$ handling for the size cap.

AdventureDeckEditor.java (the actual deck-building screen) needed no changes — it extends FDeckEditor and doesn't override CatalogPage/DeckSectionPage's filtering, so it already inherited the Mobile UI fixes above, and its own "why is this deck invalid" display already calls the shared getDeckConformanceProblem().

Cards implemented

All 12 cards in the Rulebreaker cycle:

Card	DeckRule clause	Other abilities
The Everforger	Exempt$ Artifact.Creature,Equipment,Basic.Land	Once-per-turn copy trigger for artifact creature/Equipment spells
Hadran, Naya Sunseeder	Exempt$ Creature.powerGE4	Any-color mana ability; draw on power-4+ ETB
Daxiver, Izzet Electromancer	Exempt$ Instant,Sorcery	Any-color mana restricted to instant/sorcery spells
Maular, the Next Evolution	Exempt$ Creature.cmcGE7,Basic.Land	Doubles power/toughness of attacking mv7+ creatures
Grizzlegom, Hurloon Hero	Exempt$ Land	5-clause attack trigger, one per basic land type
Tolabow, Loch Rascal	AllowedAdditionalColor$ 1 + AllowedAdditionalColorType$ Instant,Sorcery + Exempt$ Basic.Land	Prowess Otter token on instant/sorcery cast
Whtz, the Bibliophile	AdjustMax$ Unlimited	Draw+gain ability, discounted with 200+ starting cards
Valko Indorian	Exempt$ Phyrexian,Basic.Land	Phyrexian creatures you control have menace and lifelink
Valko Indorian, Researcher	Exempt$ Artifact,Enchantment	Artifacts/enchantments you own become both types, all zones; +1/+1 counter on cast
Arvad of the Weatherlight	Exempt$ Permanent.Legendary	Combat damage puts a legendary permanent from hand onto the battlefield
The Unluckiest Planeswalker	Exempt$ Aura,Basic.Land	Can be your commander; two loyalty abilities (mana+token, discard/draw/reattach)
Seluma, Light of Aysen	Exempt$ Angel,Basic.Land	Flying; combat damage reanimates an Angel

Known limitations

• DeckRule:Copies, DeckRule:Commander, DeckRule:FormatPool, etc. from #8066's fuller vision are not implemented — only ColorIdentity and Size, which is what this cycle needs.
• Advantageous Proclamation still uses its own hardcoded deck-size check rather than DeckRule:Size; migrating it wasn't attempted, to avoid double-applying the adjustment.

Code changes made with heavy assistance from Claude

[Jetz72]

How well do these hold up in Adventure Mode? It has its own enforcement logic for certain deck rules.

[tool4ever]

nice work