Combo · ENGINE

Switcheroo is a 2D swing, not a D one, and 433.1.c is the trap printed in the rules - swap the Poro, never Tryndamere

5 cards · chaos + fury · verified

Pieces

• Switcheroo ×3 SFD-145 · engine · chaos

  [Hidden] (Hide now for 1 Power of any domain to react with later for 0 Energy.) [Action] (Play on your turn or in showdowns.) Swap the Might of two units at the same battlefield this turn.

• Pouty Poro ×1 OGN-013 · enabler · fury

  [Deflect] (Opponents must pay 1 Power of any domain to choose me with a spell or ability.)

• Tryndamere, Barbarian ×1 OGN-034 · payoff · fury

  When I conquer after an attack, if you assigned 5 or more excess damage to enemy units, you score 1 point.

Payoff

Deck

• Switcheroo is mono-Chaos and both units are mono-Fury, so the identity is Fury/Chaos and 103.1.b.2 needs a legend covering both. Measured over data/cards.json, the Fury/Chaos legends are OGN-251 / OGN-301 Loose Cannon, OGS-017 Dark Child - Starter, SFD-185 / SFD-242 Glorious Executioner, UNL-185 / UNL-228 Bloodharbor Ripper and VEN-143 / VEN-191 Master of Shadows.
• None of the three is a Signature card (checked against data/cards.json), so 103.2.d.2 adds no constraint, and none is banned or restricted in either format.
• The swap needs a body of your own at the battlefield whose Might differs from the enemy defender's. Pouty Poro at 2 is the cheapest one in Fury; any other body works as long as 433.1.c is respected.

Prerequisites

• THE ARITHMETIC, AND IT IS A DOUBLE SWING. 433.1: 'Swapping is the act of increasing one numeric value and decreasing another numeric value on some number of Game Objects such that their values are reversed.' 433.1.b gives the mechanism: 'determine the difference between these values and then apply an Increase for that amount to the lower value of the two attributes, and a Decrease of that amount to the higher value.' So one card moves 2D of Might, D up on you and D down on them. Poro 2 against a Might 8 defender is D = 6: the Poro becomes 8 and the defender becomes 2.
• WHAT THAT BUYS, WITH THE QUANTITIES DECLARED. Without the swap: Tryndamere 8 plus Poro 2 is 10 summed attacking Might (465.2.c) against a Might 8 defender; 465.2.c.4 caps assignment at the minimum needed to kill, so 8 is assigned and the excess is 2 - below Tryndamere's threshold of 5. With the swap: 8 plus 8 is 16 against a Might 2 defender, 2 is assigned, and the excess is 14. Switcheroo is the entire difference between 2 excess and 14 (R28 = A: excess damage is attacking Might that never got assigned). CHECKED 2026-10-26 (#472, the follow-up PR #471 listed for #464): holds against the declared Might 8 defender, and survival is why. 383.4.c.2.a: 'The Conquer Abilities of Units are put on the Chain as Pending Items after the Unit(s) these effects correspond to are present at a Battlefield when a player gains control of it and gains 1 Victory Point from Conquering.' 365.1: 'Passive Abilities of Permanents are typically only active while on the Board.' The defender picks the deaths: 465.2.c: 'Starting with the Attacker, each player assigns an amount of damage equal to their summed Might among the other's Units.' With 465.2.c.3: 'Units must have lethal damage assigned to them in full before damage is assigned to a different Unit. Example: If a player has 5 damage to distribute among four 3 Might units, they may not choose to assign 2 damage to one of the units and 1 damage to each of the remaining 3. They must assign at least 3 damage to one, and the remaining 2 to another.' After the swap the defender is Might 2 and deals 2, which kills neither Tryndamere (8) nor the Poro (now 8), so both are present at the Conquer. The swap shrinks the garrison as well as freeing excess, and that is what bounds the line: against a garrison of summed Might G with no damage marked, whose swapped defender is Might M (above 2), the garrison deals G - M + 2 after the swap and kills Tryndamere from 8, and the excess is 6 + 2M - G. So against a Might 8 defender the point holds while the rest of the garrison sums 5 or less; from 6 beside it the defender kills Tryndamere and the attack pays the Conquer alone. Re-derived on 2026-10-26 from the rules above.
• 433.1.c IS THE TRAP AND IT IS PRINTED IN THE RULES: 'If both attributes are the same numeric value, Swapping has no effect.' Tryndamere is Might 8 and the defenders worth attacking are often Might 8. Swapping HIM with such a defender is a dead card - the swap must be made with a body whose Might differs, which is exactly why the Poro is in uses[] rather than in a notable.
• IT IS A SNAPSHOT, NOT A MIRROR. 433.1.a: 'Swapping creates two different effects that apply to each attribute. One that Increases one value and one that Decreases the other. These effects last for the duration specified by the effect that instructed the Swap.' The +6 and the -6 are fixed at the instant of the swap and then ride as ordinary modifiers for the turn, so a later pump on the defender does NOT re-swap and a later pump on your Poro stacks on top. 477.3.e.2.a puts the -6 last among the arithmetic, after every increase.
• THE FREE [HIDDEN] MODE IS DEFENSIVE ONLY. 811.1.b hides a card 'at a battlefield you control', and 811.1.d.2 confines a hidden card's play-effect targets to that battlefield. The battlefield you are ATTACKING is by definition not one you control, so the 0-Energy mode can only fire on defence. Attacking, Switcheroo is played from hand for 2 Energy and 2 Power - and 155 plus 806.1.b let an [Action] spell be played inside the combat showdown, i.e. after the Attacker designation and after the opponent has committed.
• AND THE SWAP READS CURRENT MIGHT, SO ORDER IT LAST. 433.1.b takes the difference between the two values as they stand, so any [Assault] the Poro has gained (807.1.c, 'While I am an attacker, I have +X [M]') is already in the number being swapped away. Cast Switcheroo after every pump has landed, not before.

Steps

1. Play OGN-013 Pouty Poro (2 Energy) and OGN-034 Tryndamere, Barbarian (7 Energy + 2 Power); 143.4 has them enter exhausted, so they attack from the following turn.
2. Standard-move both to the enemy battlefield (144.3 makes multiple simultaneous Standard Moves one action to a shared destination). Contested applies (190.3.a.1), the Combat is staged (323.9) and opens (323.13), and 464.2.c.3 designates them Attackers.
3. Inside the opened Combat Showdown, play SFD-145 Switcheroo from hand for 2 Energy + 2 Power (155, 806.1.b, 464.2.f.1). Choose the Poro and the enemy defender - never Tryndamere, per 433.1.c.
4. 433.1.b resolves it as +6 to the Poro and -6 to the defender for the turn: the Poro is Might 8 and the defender is Might 2.
5. The damage step assigns the defender its minimum lethal 2 out of your 16 summed Might (465.2.c, 465.2.c.4), leaving 14 excess assigned to enemy units.
6. You win the combat and Conquer (466.5, 466.5.d). Tryndamere's trigger checks 'if you assigned 5 or more excess damage' and you score 1 point (194.1.c; R2 = A makes that a point Gain by ability, not a 469 Score).

Per iteration

one Switcheroo turns a 2-excess attack into a 14-excess one, which is the difference between Tryndamere firing and not firing

How it ends

one point per Conquer, and 470 caps Scoring at one per battlefield per turn with 485.4 putting two battlefields on a Duel table; three Switcheroo (103.2.b) is three such turns - an engine, not a burst

Sources

Published elsewhere

• Riftbound Core Rules, Last Updated 2026-07-16 (data/Riftbound-Core-Rules-2026-07-16.txt), 433.1.b 2026-07-16
• Riftbound Core Rules, Last Updated 2026-07-16 (data/Riftbound-Core-Rules-2026-07-16.txt), 433.1.c 2026-07-16
• Riftbound Core Rules, Last Updated 2026-07-16 (data/Riftbound-Core-Rules-2026-07-16.txt), 433.1.a 2026-07-16

Walked here, in this project

• Hand walk 2026-09-07 2026-09-07 record

Walked against Core Rules 2026-07-16

Match a deck list against the whole catalogue