Combo · ENGINE

Katarina's ceiling is the board, not the deck — 811.1.b allows one facedown card per battlefield, and the Trap doubles only her SECOND trigger

3 cards · fury · verified

Pieces

• Katarina, Reckless ×1 UNL-023 · payoff · fury

  When you hide a card, ready me. When you play a card from face down, deal 2 to an enemy unit.

• Lotus Trap ×1 UNL-013 · engine · fury

  [Hidden] (Hide now for 1 Power of any domain to react with later for 0 Energy.) [Reaction] (Play any time, even before spells and abilities resolve.) Choose a unit. Double all damage that would be dealt to it this turn.

• Sudden Storm ×1 SFD-017 · engine · fury

  [Hidden] (Hide now for 1 Power of any domain to react with later for 0 Energy.) [Action] (Play on your turn or in showdowns.) Deal 2 to a unit at a battlefield. If it's attacking, deal 4 to it instead.

Payoff

Deck

• Any legend with Fury among its two domains (103.1.b.3) — 16 names: Daughter of the Void (OGN-247), Relentless Storm (OGN-249), Loose Cannon (OGN-251), Hand of Noxus (OGN-253), Dark Child - Starter (OGS-017), Mechanized Menace (SFD-181), Purifier (SFD-183), Glorious Executioner (SFD-185), Void Burrower (SFD-187), Virtuoso (UNL-181), Pridestalker (UNL-183), Bloodharbor Ripper (UNL-185), Piltover Enforcer (UNL-187), Rogue Assassin (VEN-139), Butcher of the Sands (VEN-141), Master of Shadows (VEN-143).
• Control of BOTH battlefields (485.4), because 811.1.b allows only one facedown card per battlefield — with one battlefield the line cannot exist.
• Two turns of setup: 1 rainbow to hide each card, one at each battlefield.

Prerequisites

• THE CEILING IS PRINTED IN THE KEYWORD AND IT IS EASY TO MISS. 811.1.b: you may hide a card 'at a battlefield you control **that doesn't already have a facedown card hidden there** for as long as you control that battlefield.' One facedown card per battlefield, and 485.4 puts two battlefields on a Duel table. So Katarina's 'When you play a card from face down' fires AT MOST TWICE A TURN however many [Hidden] cards the deck holds, and only if you control both battlefields — with one battlefield she is worth 2 damage a turn, full stop. Three copies of anything (103.2.b) does not move that number.
• THE TRAP CANNOT DOUBLE ITS OWN ARRIVAL, AND THE CHAIN SAYS WHY. Playing Lotus Trap from face down is the event Katarina watches, so her trigger is Finalized above the still-pending spell and 340.1 ('The newest Finalized Chain Item resolves') runs her 2 damage BEFORE the doubling is in place. The Trap therefore pays on the SECOND facedown play of the turn and on nothing else: that second trigger's 2 becomes 4. Total from Katarina in one turn: 2 + 4 = 6, for zero Energy. (R26 on issue #11 was ruled the other way for a 'when you play a spell' trigger, on 359.3.e.10's example; if that reading were extended to 'when you play a card from face down' the first 2 would also double and the total would be 8. The entry stands on the floor of 6 and does not need the reading.)
• AND THE TWO HALVES CANNOT SHARE A TARGET, WHICH IS THE REAL LIMIT. 811.1.d.2 confines a hidden spell's targets to the battlefield it was hidden at, so the Trap's 'Choose a unit' is stuck at battlefield A and Sudden Storm's 'a unit at a battlefield' is stuck at B. Sudden Storm's own 4 damage can never be doubled by this Trap. What CAN cross is Katarina's own 2 — her trigger is not a hidden card's play effect, so 811.1.d does not reach it, and it may be aimed at the Trap's chosen unit at A even though the card that triggered it was played at B.
• So the turn reads: 6 damage into one enemy unit at A (2 undoubled + 4 doubled) and 4 into an attacking enemy unit at B, for zero Energy and two rainbow paid on earlier turns. 143.2.a kills at Might, so that clears a 6-Might body and a 4-Might attacker in one Closed State.
• Both cards reach the opponent's turn, by different routes: 811.1.b grants [Reaction] to every hidden card once face down (813.1.c.1, any Closed State), and Sudden Storm additionally prints [Action] (806.1.b, Showdowns) — but it is 811.1.b that is doing the work here, since the cards are being played FROM face down.
• 'Double all damage that would be dealt to it this turn' is not restricted to your damage: the opponent's combat damage into that unit doubles too, which is irrelevant when the unit is theirs and a real hazard if you ever choose one of your own.
• Order of play matters and is not obvious: the Trap must be the FIRST facedown play of the turn. Played second, its doubling arrives after both of Katarina's triggers have resolved and the entry is worth 4 instead of 10.
• 419.4.a IS THE PARAGRAPH, NOT THE EXAMPLE. R26 was ruled B on the strength of the worked example at 359.3.e.10, and 419.4 opens "Some Abilities trigger when cards are played or otherwise check whether cards have been played" with 419.4.a stating it normatively: "Any such triggered abilities trigger when the act of playing the card has been completed by the resolution of the card." So the conclusion is unchanged and its footing is not an example any more - only a rewording of 419.4.a could reopen R26, not a rewording of 359.3.e.10. Companion: 419.4.a.1 keeps the trigger off a countered card, while 419.4.b lets a non-triggered check (Legion, "cards played this turn") count it - a trigger needs RESOLUTION, a non-triggered check needs only FINALIZATION.

Steps

1. Control both battlefields. On separate turns, pay 1 rainbow each to hide Lotus Trap at battlefield A and Sudden Storm at battlefield B (811.1.b — one facedown per battlefield).
2. On the opponent's turn, in the Closed State their attack opens, play Lotus Trap from face down for 0 Energy.
3. Katarina's trigger is Finalized above it and resolves first (340.1): 2 damage to an enemy unit, undoubled. Aim it at the unit you are about to choose with the Trap.
4. The Trap resolves: choose that enemy unit at A (811.1.d.2 confines it there). All damage dealt to it this turn is now doubled.
5. Play Sudden Storm from face down for 0 Energy. Katarina's trigger fires again: 2 damage aimed at the same unit at A, doubled to 4 — her ability is not confined by 811.1.d.
6. Sudden Storm resolves at its own battlefield: 4 damage to an attacking enemy unit at B (2 doubled by the card's own attacking clause, not by the Trap).

Per iteration

-2 cards, -2 rainbow paid on earlier turns, 6 damage at one battlefield and 4 at the other

How it ends

engine — 6 damage into one unit and 4 into another, for zero Energy on the turn, twice a turn at most (811.1.b's one facedown per battlefield); nothing here scores

Sources

Published elsewhere

• Riftbound Core Rules, Last Updated 2026-07-16 (data/Riftbound-Core-Rules-2026-07-16.txt) 2026-07-16

Walked here, in this project

• Hand walk 2026-09-07, issue #169 — matrix families rows 6-18, second pass 2026-09-07 record

Walked against Core Rules 2026-07-16

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