Combo · ENGINE

Rek'Sai, Swarm Queen reveals Undertitans — Energy on every attack

4 cards · order · verified

Pieces

• Rek'Sai, Swarm Queen ×1 SFD-170 · engine · order

  When I attack, you may reveal the top 2 cards of your Main Deck. You may banish one, then play it. If it is a unit, you may play it here. Recycle the rest.

• Undertitan ×3 SFD-175 · payoff · order

  When you play me, give your other units +2 Might this turn. As I'm revealed from your deck, [Add] 2 Energy.

Payoff

Deck

• Legend domains cover Order for the core; the named readiers are Fury, so the real pair is Fury/Order (Piltover Enforcer UNL-187 or Hand of Noxus OGN-253).

Prerequisites

• Needs three Undertitans and an otherwise empty Main Deck. The Draw Phase strips one card per turn, so three copies buys exactly one clean turn at +4E per reveal; the next turn the deck holds one card and each reveal is +2E, then zero, and the turn after that the Draw Phase itself is a Burn Out (431.1.a, 431.2).
• Revealing more cards than the deck holds is explicitly NOT a Burn Out (431.1.c) — you reveal as many as possible and carry on. Only drawing past the end costs a point.
• One reveal per combat and Rek'Sai has no Ganking, so in Duel's two battlefields the reliable number is two reveals a turn, +8E. Whether 'Recycle the rest' still recycles when nothing was banished is R22; the other reading leaves both Undertitans on top and makes the engine stronger.
• CITATION UPGRADE (2026-09-09): 369.1 is the paragraph that makes Undertitan’s “As I’m revealed” a Replacement Effect rather than a trigger, and Riot names the card in the example - which is why the reveal and the Add are one event and nothing can respond between them.
• 370.1.b.1 NAMES THIS CARD IN ITS OWN WORKED EXAMPLE AND WAS UNCITED HERE (upgrade 2026-09-12; a debt two separate lanes flagged). An *"as you look at or reveal me"* clause is a REPLACEMENT EFFECT, not a Triggered Ability: 370.1.b.1 - *"In the case of Replacement Effects that describe a game action to occur `as` an event occurs, the described event is replaced by that same event plus the game action being performed"* - and 371.2 is what makes its *"you may"* legal. Three consequences a trigger would not buy: there is **no Chain Item**, so no window exists between the look and the body arriving; it is **immune to every trigger multiplier in the pool** (`OGN-236 Karthus` doubles Deathknells, `UNL-087 Blue Sentinel` and `UNL-029 Red Brambleback` double Hold and Conquer triggers, and none of them can see a replacement); and 431.1.c keeps the look itself free of Burn Out.
• WHY AN ABILITY ON A CARD NOBODY HAS PLAYED WORKS AT ALL, WHICH THIS FAMILY CITED FOR NEITHER (upgrade 2026-09-12, #187 batch 15). Every entry in the Undertitan/Nocturne family cites 370.1.b.1, which says what KIND of ability it is and nothing about why it is active in the Main Deck. Three paragraphs answer that: **365.1 is the DEFAULT that would kill the family** - *"Passive Abilities of Permanents are typically only active while on the Board"*; **366.1 is the OVERRIDE** - *"Passive Abilities of cards in zones that are outside of the Board will self-describe their context"* - which was cited by TWO entries out of 762, neither of them here; and **368.1** - *"Passive Abilities can be Replacement Effects"* - had ZERO citations anywhere and is the hinge, because it is what makes 366.1 rather than 385.1 the applicable block. This project carries 385.1 and 385.2, the TRIGGERED-outside-the-board pair, at 16 and 42 citations and had never had the passive counterpart, so a reader reaches for 385 and gets the wrong block. **424.1.a.2** completes it - cards remain in the zone they are being Revealed from, with Riot naming the top of the Main Deck - which is why the self-described context is satisfied at the instant the passive fires.
• 370.3 IS THE NARROWEST AND MOST ON-POINT PARAGRAPH FOR THIS CARD AND IT WAS MISSING FROM THE WHOLE FAMILY (self-audit upgrade 2026-09-12, #187 batch 20). The earlier pass prescribed 365.1, 366.1, 368.1 and 424.1.a.2, which are about PASSIVE ABILITIES IN GENERAL. **370.3 is about REPLACEMENT EFFECTS AND ZONES SPECIFICALLY**: *"If a Game Object has a Replacement Effect that is active in a specific zone, it is evaluated and subsequently applied if it enters that zone before an event occurs that it could replace."* Measured on 2026-09-12 it was cited by **exactly ONE entry in 762** and by none of this family. 366.1 says a passive outside the board self-describes its context; 370.3 says a replacement effect can be ACTIVE IN A ZONE and is applied if the object entered that zone first - and for a card sitting in the Main Deck since the game began that timing half is free, **which is exactly why it is easy to leave out** and why its worked example is the case where the half BITES.

Steps

1. Rek'Sai attacks: reveal the top two Undertitans, +2E each. Decline the banish — 'banish one, then play it' is a single package and the play costs 6E+1P — so both recycle to the bottom of a two-card deck and are the same top two next attack.
2. Ready Rek'Sai for a second attack. Twilight Reveler (VEN-020) readies her inside the combat; Piltover Enforcer (UNL-187) needs a conquer with 3+ excess damage, which is the case where she is not recalled and has to walk home first. She is already Mighty at 5, so Fiora, Worthy never triggers for her (709).

How it ends

engine only — +4 Energy per reveal on the one turn the deck still holds two Undertitans, about +8E across two attacks, decaying to +2E and then nothing on following turns

Sources

Walked here, in this project

• Hunt v2 lens L3, entry L3-11 2026-09-03 record
• REFUTE pass 2, 2026-09-03 2026-09-03 record
• Hand walk 2026-09-04 2026-09-04 record
• Hand check against Core Rules 2026-07-16 (data/Riftbound-Core-Rules-2026-07-16.txt), manager citation pass 2026-09-09

Walked against Core Rules 2026-07-16

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