Dune/docs/NEXUS_CARD_RULES.md

Nexus cards: primary-source contract

Source audit, 10 September 2026. This document establishes the printed component inventory and implementation contract; it does not claim runtime support or lift expansion release gates. The ordinary worm-triggered alliance Nexus already in the engine is distinct from this optional card module.

Authority and acquisition

• GF9 Ecaz & Moritani rulebook, printed pp.4, 9, 11 and 16: component count, independent variants, common lifecycle, Atreides example and two Nexus FAQ answers. Official-domain indexed text was inspected, but direct retrieval returned 403 during this audit. The coordinator successfully fetched the publisher-authored PDF mirror to /tmp/dune-e3-nexus-rules.pdf and .txt. This is a mirror of the publisher's rules, not a separate rules authority.
• Photograph of all twelve printed Nexus cards, uploaded by Jaakko / zaksalo on 2 October 2023. The original 3024×4032 photograph was downloaded and visually inspected, including all three panels on every card. The authority is the photographed publisher-authored component text, not the uploader's commentary. Original image; temporary inspection copy /tmp/dune-nexus-cards.jpg.
• Atreides' physical face independently matches the example on printed p.11. All twelve faces carry the 2022 Legendary notice and the E3 expansion mark. This is the original E3 module, not a later edition or fan revision.

Search also encountered tournament compilations that change the draw procedure and add effects. They were not used as authority. The former dunecards.com reference currently resolves to an unrelated collectibles storefront and is not a usable component source.

Publisher's common rules

The module contains twelve cards and can accompany any faction selection, independently of the other variants. At the end of Spice Blow and Nexus, if a Nexus happened and an alliance exists, unallied players may draw, or replace their held card. Draws follow alliance negotiations. Cards stay secret until use and are discarded afterward; joining an alliance also requires discarding the held card. Exhaustion recycles shuffled discards. Drawing one's own faction allows an immediate optional replacement in Basic and Advanced.

Each card has mutually exclusive modes: Cunning for its native player, Betrayal when another player controls that faction, and Secret Ally when the faction is absent. The printed FAQ requires Bene Gesserit Secret Ally before Prescience; cards retained by Tleilaxu through Harkonnen Secret Ally are Face Dancers. GF9, pp.4, 9, 11, 16

Executable lifecycle composition

These are implementation consequences of the common rule, rather than additional quotations:

1. Keep a separate twelve-identity deck, discard and at-most-one held card per player. This is not a Treachery Card: no Treachery hand-limit slot, auction, ordinary discard hook, CHOAM sale, or Ecaz poison receipt follows from holding or discarding one.
2. Initialize only when this variant is selected. Include cards for absent factions; removing them would eliminate Secret Ally. No initial deal is prescribed. Use the twelve photographed factions exactly: Atreides, Bene Gesserit, Emperor, Fremen, Harkonnen, Spacing Guild, Ixians, Tleilaxu, CHOAM, Richese, Ecaz, Moritani.
3. Preserve a phase-level nexusOccurred fact separately from the transient negotiation flag. The explicit draw trigger is the end of the whole phase. Advanced blow A alone must not issue a draw, and blow B must not erase an earlier qualifying Nexus. Evaluate the final alliances when opening the opportunity.
4. A player with no card can draw or decline; one with a card can keep it or discard-and-replace. These are one opportunity, not repeated replacements. The printed own-faction redraw permission is implemented by a private preference selected before the draw: keep any card, redraw one's faction once, or redraw whenever one's faction appears. The server performs that policy atomically without a later confirmation. This automation prevents a public waiting state from identifying an own-faction draw. It is not an anytime exchange of a previously kept card, and it does not filter that faction out of the physical deck.
5. One event must survive the complete draw policy, reload and uncertain responses. Store the actual final card and physical intermediate discards before projecting the result. Randomness is not rerun when reading, normalizing, reconnecting or retrying the same committed action. Own-faction and other-faction draws complete the same public opportunity; no private redraw decision remains to reveal the drawn identity through public phase progress.
6. All actual alliance producers must discard both incoming partners' held cards as part of the accepted alliance transaction: ordinary Nexus, Ecaz Ambassador and Moritani's alliance offer. An offer, refusal or canceled formation does not discard. Leaving an alliance does not independently generate a draw.
7. Secret Ally selects the card's effect; it does not create a real allied player, change the stronghold victory target, unlock generic ally transfers or provide every ability of the absent faction.
8. Native roster identity determines the mode. A stolen leader, alliance benefit, Ghola or temporary battle controller does not change one's faction.
9. Public views may expose the module's inventory and readable reference for all twelve faces. Held identities, own-faction redraw eligibility and source deck order remain private. A public action list must not reveal which opponents hold a relevant Betrayal. Card play and its ensuing action need a saved original-effect commitment so a discarded card is not consumed twice.

The text does not specify a Nexus-dealing seat order. A deterministic storm-order serializer can be documented as implementation ordering under the game's general precedence convention, not attributed to a special Nexus instruction. It must not replace secret dealing with publicly revealed batches.

All twelve printed effect contracts

Every row below is a semantic transcription of the photographed face, not a reproduction of its prose. Alternative effects within a panel consume the same single Nexus card. Timings below come from that panel; where a panel does not state an explicit phase, do not invent one from a similarly named faction ability.

Card	Betrayal: opposing native faction seated	Cunning: native player	Secret Ally: faction absent
Atreides	Stop Atreides' attempt to inspect one battle-plan element.	Obtain a second element from the battle opponent.	In one's battle, choose one opposing plan element to inspect: leader, weapon, defense or dial.
Bene Gesserit	Stop Voice.	During one's Shipment and Movement action, convert any selected advisor groups to fighters; each territory must finish with a single stance.	Use Voice against one's battle opponent. The official FAQ places this before Prescience.
Emperor	During Bidding, require Emperor to cover the ally's purchase, at least the necessary spice; alternatively suppress Sardaukar while battle plans are being made.	Before making a battle plan, treat five own forces as Sardaukar when that battle contains none.	On a Treachery purchase, retain the spice after demonstrating the required funds; alternatively revive three extra forces free beyond the normal limit during Revival.
Fremen	Suppress worm riding for this turn, or suppress the two-territory movement advantage during Shipment and Movement.	A worm appearing in a territory without forces permits a group from one desert territory to ride elsewhere, respecting storm and occupancy.	Protect one's forces from a worm, or revive three forces free during Revival.
Harkonnen	Cancel a revealed Harkonnen traitor, shuffle that identity into the Traitor Deck, and give Harkonnen a replacement draw during Mentat Pause.	At any time, draw a Traitor Card into the hand, then choose one held Traitor Card to shuffle back.	During Mentat Pause draw two Traitor Cards, then choose two held cards to shuffle back. Tleilaxu's retained card is a Face Dancer under the official FAQ.
Spacing Guild	Take one entire shipment payment otherwise owed to Guild or bank, including one's own payment. The face expressly overrides income for occupying Junction.	Immediately after one's Shipment and Movement, make a second shipment. That group cannot move unless Hajr permits it.	Use Guild shipping prices; cross-shipping or returning to reserves is allowed as the shipping action.
Ixians	Prevent either the Bidding advantage or Technology advantage; one card cannot cancel both.	Before making one's battle plan, give every Suboid full unsupported strength in all battles for the remainder of this turn.	Discard a just-purchased Bidding Treachery Card and take the next Treachery deck card.
Tleilaxu	Cancel a revealed Face Dancer. It stays revealed until all Face Dancers have been revealed.	Set all revealed Face Dancers aside, secretly replace them, then shuffle the set-aside identities into the Traitor Deck.	During Revival, revive an own leader free and up to five forces at one spice each.
CHOAM	Make CHOAM discard a random held card without earning spice for that discard.	Spend any Treachery Card to obtain a selected Worthless special effect.	During Collection, trade a Worthless card for two spice; alternatively after winning a battle privately inspect a random opposing held card that was not used in that battle.
Richese	Stop a Richese self-purchase by discarding its intended Richese card without payment; alternatively divert payment for a Richese sale to the bank.	Combine two No-Fields in one shipment, still priced as one force; reveal one immediately and put it in front of the shield.	Replace normal shipping with a reserve shipment of up to five forces priced as one.
Ecaz	Before Shipment and Movement, where Ecaz and ally share a territory, make the ally return its forces from one such territory to reserves.	Take Duke Vidal for the current turn even from capture, Tanks or Ghola custody, overriding Moritani; set him aside at turn end.	Make one player disclose whether any of one's leaders are among their traitors, without identifying those leaders.
Moritani	Return a board Terror token to Moritani without revealing it.	When placing a Terror token, permit any Arrakis territory, including an existing Terror location.	After losing a battle with a winner, retain one played Treachery Card that could have been retained after winning.

Source for the entire table: the twelve original printed components. All card identities appear once; the photograph is arranged Moritani/Tleilaxu/Richese/Ixians, Atreides/Bene Gesserit/CHOAM/Emperor, Guild/Ecaz/Harkonnen/Fremen.

Effect integration boundaries

Later focused source contracts cover Emperor strength, purchases and revival, Ixian purchased-card replacement, and Fremen worm and revival effects. These audits distinguish implemented work from remaining source/timing questions; the current runtime evidence is tracked in implementation status.

Atreides is the first complete effect family to implement. It has independent rulebook and physical-face evidence, and the engine already has private plan-element inspection. The Nexus effect needs its own cause and receipt rather than temporarily changing the inspecting faction. The second element must differ from the already inspected element. Preserve the original disclosed value if an allowed later battle edit occurs; follow the existing plan commitment rules instead of refreshing an old observation. The card specifies an element, not the entire hand or battle plan. A weapon/defense request uses actual played-card classification, including the published Reinforcements/Harass exclusions, rather than leaking a card merely because it occupies that slot.

Cancellation needs the original attempted effect. Betrayal is not a blanket Karama flag. For Atreides, identify the inspection attempt being prevented; for Voice, the command; for a traitor/Face Dancer, the actual revealed identity; for economy, the original invoice and settlement. Do not refund or replay a completed payment merely because the next input happens to be a Nexus play. Effects with no printed phase still need a safe explicit action boundary and cannot bypass another player's committed private choice.

Physical custody remains authoritative. Replacement Traitor Cards, Face Dancers, discarded Treachery Cards, reserve groups and Duke Vidal are existing components. Draw first then return cards in the order stated; do not shuffle a just-set-aside Face Dancer early enough to redraw it as its own replacement. The Nexus card does not generate an additional Duke disc or additional physical Sardaukar. Virtual Sardaukar strength belongs to battle modifiers, not a change to elite counter custody. A canceled Harkonnen traitor owes a later replacement even after the original battle is finished.

Delayed effects outlive card custody. Turn-long Suboid strength, Fremen riding prevention, Harkonnen's Mentat replacement, Guild's extra shipment and Ecaz's temporary Duke claim need saved receipts. Discarding the Nexus card cannot erase those commitments, and drawing another cannot replay them. Moritani retention must join the existing winner/loser card-retention sequence without retaining mandatory-discard Tooth or Artillery merely because a weapon slot was used.

Existing unresolved rules stay local. Guild Betrayal's explicit Junction override is not a ruling for ordinary low-Junction contribution rounding. Moritani Betrayal's explicit return-to-supply instruction is not evidence that high-Grumman's differently worded removal returns a token. Free Nexus revival effects need source identity and original newly revived groups for Homeworld interactions; they are not ordinary free revival by default. Do not silently resolve the pending Southern Hemisphere threshold/splitting questions or Ix revival shortage question through a Nexus adapter.

Remaining source questions and release boundaries

• The common trigger is the end of the full Spice Blow and Nexus phase. The later shorthand about the next Nexus is read with that opening condition; it does not establish an extra draw after each Advanced blow. Keep that implementation decision explicit in runtime documentation.
• No retrieved card or E3 FAQ gives a general rule that every Nexus effect is Karama-immune, or that playing one suspends all ordinary responses. Homeworld immunity on the preceding page is limited to Homeworld advantages/penalties. Audit cancellation of an underlying native advantage separately from cancellation of the Nexus card before enabling each family.
• Duration is explicit for several panels but not all. Ixian Betrayal's scope over multiple auction lots, the optional continuation after canceling native Prescience, and exact multi-party cancellation priority require the corresponding existing faction timing contract. Do not make an entire-phase cancellation merely from the word “advantage.”
• Emperor forced ally payment needs a precise invoice allocation when the ally has some funds and Emperor is short. Its own purchase-refund alternative also needs original payer contributions. Tleilaxu's combined leader/force revival requires an audit of partial selection and interaction with ordinary free rates; the card does not say that all five force revivals are free.
• Richese's two-No-Field effect needs its own physical counter and immediate-reveal transaction; the normal single-marker action cannot represent it by adding private values. Ecaz's Duke override needs explicit restoration/end-turn handling across capture, death and Ghola records. These are material implementation tasks, not reasons to invent substitute effects.
• A complete twelve-card reference/inventory and common lifecycle are substantial first work, but do not alone make all thirty-six panels playable. Keep the public module release gated until every face's supported timing, secrecy, custody, bots, UI, rejection, multiplayer CAS and saved continuation paths are verified. If development supports only Atreides' family first, other faces must remain accurately represented and explicitly unavailable in the audit mode; they must not silently act as blanks in a released module.

No user question was sent during this audit. No tournament rule, fan effect, public predeal reveal, extra Nexus identity or Discoveries prerequisite has been adopted.

Moritani Secret Ally retention timing

14 September follow-up. The recorded physical card permits retaining one otherwise retainable played Treachery Card after losing a battle with a winner; mandatory discards stay excluded. The existing Moritani alliance retention quote, card selection and saved discard continuation can supply the physical operation, but do not supply a private opportunity to use a hidden Nexus card.

Automatically continuing a loser without the card while pausing a holder reveals custody through the table's progress. Calling both paths the same cleanup boundary does not hide that difference. Committing before the result moves the printed after-loss choice earlier. A universal loser confirmation requires the same pending product exception as other hidden optional reactions. Keep this effect unavailable until that shared response policy is resolved; no new outcome ruling or duplicate user question is introduced by this audit.