Combo · ENGINE

Fox-Fire's threshold is a SUM, so lowering Might is how you widen the sweep — three cards turn a 4 Might cap into four bodies

5 cards · calm + mind · verified

Pieces

• Fox-Fire ×3 OGN-256 · payoff · calm/mind

  [Hidden] (Hide now for 1 Power of any domain to react with later for 0 Energy.) [Action] (Play on your turn or in showdowns.) Kill any number of units at a battlefield with total Might 4 or less.

• Ahri, Inquisitive ×1 OGN-119 · engine · mind

  When I attack or defend, give an enemy unit here -2 Might this turn, to a minimum of 1 Might.

• Nine-Tailed Fox ×1 OGN-255 · legend · calm/mind

  When an enemy unit attacks a battlefield you control, give it -1 Might this turn, to a minimum of 1 Might.

Payoff

Deck

• Legend domains are Nine-Tailed Fox's own, Calm and Mind; Ahri, Inquisitive is Mind and Fox-Fire is Calm/Mind.
• The reducers only fire in combat — Ahri on an attack or a defence, the legend on an enemy attack against a battlefield you control — so the sweep is a combat trick, not a Main Phase button.

Prerequisites

• THE MECHANIC IS THE THRESHOLD, AND NO LENS OF THIS PROJECT HAS SWEPT IT. Fox-Fire reads 'Kill any number of units at a battlefield with total Might 4 or less'. Every other removal in the catalogue is priced per unit; this one is priced on the sum of the group you name, so a card that lowers Might is not making the kill easier, it is making the GROUP BIGGER. 710 is the rule that makes the reduction count: 'Units on the board are evaluated according to their current Might.'
• ARITHMETIC WITH THE QUANTITIES DECLARED, WORKED ON A REAL BOARD. Two enemy 3 Might bodies sum to 6 and Fox-Fire cannot touch them. Ahri's -2 on one of them makes it 1 + 3 = 4: both die. Add the legend's -1 on an attacker and a 3/3/3 garrison becomes 1 + 3 + 3 = 7, still too much for one Fox-Fire — but 1 + 1 + 3 with two reducers is 5, and with both reducers on the two biggest it is 1 + 1 + 3 = 5. The honest ceiling is the floor: 'to a minimum of 1 [M]' on both cards means FOUR units at 1 Might sum to exactly 4, and that is the largest sweep this line can ever make.
• THE FLOOR CLAUSE IS ON BOTH REDUCERS AND IT IS WHAT BOUNDS THE ENTRY. Ahri and the legend each say 'to a minimum of 1 [M]', so no amount of stacking takes a unit to 0 and the sum can never be driven below the number of units. That is why the answer is four bodies and not an arbitrary number.
• [Hidden] CONFINES THE SWEEP TO THE BATTLEFIELD IT WAS HIDDEN AT, AND THE ESCAPE CLAUSE DOES NOT APPLY. 811.1.d.2: 'If a hidden spell or a play effect of a hidden permanent chooses any targets, those targets must be chosen from among options at that battlefield, unless the ability explicitly restricts targeting in a way that makes this impossible.' Fox-Fire names no other location, so played from Hidden it must sweep the battlefield where it sits. Played normally (811.3: 'at its normal timing with no restrictions on targeting') it reaches any battlefield for its full 3 Energy.
• THE PRICE OF HIDING IT, AND THE RISK. 811.1.b: 1 rainbow Power to hide it facedown at a battlefield you control, and only 'beginning on the next turn' does it gain [Reaction] and become playable for 0 Energy. 323.7 is the risk — a hidden card at a battlefield you stop controlling is removed and trashed at the next Cleanup. One facedown per battlefield, so at most one Fox-Fire is discounted at a time.
• [Action] AND [Reaction] ARE WHY THE REDUCERS AND THE SWEEP MEET. Ahri's and the legend's triggers fire during combat; Fox-Fire is [Action], which 806.1.c.1 makes playable during showdowns, and [Hidden] gives it [Reaction] while facedown (811.6). So the -2 and the -1 are still on when the sweep resolves — both say 'this turn'.
• THE FOUR-BODY CEILING IS SCOPED TO THIS LINE'S TWO FLOORED REDUCERS (added 2026-09-06 walking issue #97). Both OGN-119 and the legend print 'to a minimum of 1 [M]', which is why the sum can never fall below the number of units. It is NOT a fact about Fox-Fire. 143.2.b: 'If a unit's Might is ever less than 0, it is treated as 0 when referenced by spells and abilities' - so an UNFLOORED reduction contributes 0 to Fox-Fire's sum, not 1, and the ceiling does not bind. SFD-066 Frigid Touch (-2, [Repeat]), UNL-063 Eclipse (-4) and UNL-066 Moonlight Affliction (-10) are all Mind, all unfloored and all inside this entry's own Calm/Mind identity. That version is authored separately as foxfire-unfloored-reduction-sweep, because its reducers are one-shot spells rather than the free combat triggers this line runs on. Nothing about this entry's class, quantities or steps changes.
• AN "ATTACK OR DEFEND" TRIGGER FIRES TWICE PER TURN CYCLE, AND THIS ENTRY PRICED IT AT HALF RATE (citation upgrade 2026-09-12, #187/300-499 lane). 383.4.e defines an Attack Trigger as firing when a Unit or PLAYER gains the Attacker designation for the first time during a combat, and 383.4.f is the identical sentence for the Defender - so a card worded *"when I attack or defend"* satisfies BOTH definitions and is an Attack Trigger AND a Defend Trigger, exactly the shape the rules state outright for the other pair at 823.1.b (*"Hunt is both a Conquer and a Hold effect"*). The honest rate is once on your turn attacking and once on theirs defending. Measured across the catalogue on 2026-09-12, SIX entries use an attack-or-defend card and not one cited both paragraphs. Two limits that keep it from running away: 383.4.e.2.a checks the condition ONCE PER COMBAT despite a unit gaining and losing the designation several times in it (383.4.f.2.a is the mirror), so blinking a carrier out of a combat and back re-fires nothing; and the whole attack side is UNIT-keyed - the pool prints ZERO cards worded *"when you attack"* against FOUR on the defend side, three of them battlefields - which is why a battlefield can carry a defend trigger at all and never an attack one.

Steps

1. Have Ahri, Inquisitive at a battlefield and Nine-Tailed Fox as your legend. Optionally hide a Fox-Fire there for 1 rainbow Power a turn ahead (811.1.b).
2. Combat starts. The legend gives each enemy attacking a battlefield you control -1 Might this turn, to a minimum of 1.
3. Ahri's attack-or-defend trigger gives one enemy unit there -2 Might this turn, to a minimum of 1.
4. Add up the enemy bodies you want gone at their CURRENT Might (710). If the sum is 4 or less, play Fox-Fire — for 0 Energy if it was hidden there, 3 Energy otherwise.
5. Kill all of them at once. The largest this line ever reaches is four units, because both reducers stop at 1 Might each.

Per iteration

one Fox-Fire kills every enemy body at a battlefield whose CURRENT Might sums to 4 or less — up to four units once the two reducers have run

How it ends

engine only — three Fox-Fires, each consumed, and both reducers floor at 1 Might, so four bodies is the arithmetic ceiling of the sweep

Sources

Published elsewhere

• Riftbound Core Rules, Last Updated 2026-07-16 (data/Riftbound-Core-Rules-2026-07-16.txt) 2026-07-16
• Corpus de 8.307 listas de torneo — issue #89 (GitHub) 2026-09-06
• Lente de buff y Might — issue #97 (GitHub) 2026-09-06

Walked here, in this project

• Hand walk 2026-09-06 2026-09-06 record
• Hand walk 2026-09-06 2026-09-06 record

Walked against Core Rules 2026-07-16

Match a deck list against the whole catalogue