Combo · ENGINE

Two Kha'Zix on one board: the lone-enemy attack banks the XP, and the other one spends it as removal

3 cards · body + chaos · verified

Pieces

• Voidreaver ×1 UNL-201 · legend · body/chaos

  When you win a combat, gain 1 XP. Spend 1 XP, Exhaust: [Buff] a unit. Spend 2 XP, Exhaust: Move an exhausted friendly unit from a battlefield to its base.

• Kha'Zix, Mutating Horror ×1 UNL-143 · engine · chaos

  [Ambush] (You may play me as a [Reaction] to a battlefield where you have units.) When I attack or defend, if an enemy unit is alone here, give me +2 Might this turn and gain 2 XP.

• Kha'Zix, Evolving Hunter ×1 UNL-119 · payoff · body

  [Hunt] (When I conquer or hold, gain 1 XP.) When I attack, you may spend 3 XP to deal damage equal to my Might to an enemy unit here.

Payoff

Deck

• Voidreaver is the legend, so the Domain Identity is Body/Chaos (103.1.b.2). UNL-119 is mono-Body and UNL-143 is mono-Chaos, and 103.1.b.3 admits a single-domain card into any identity containing it.
• Both Kha'Zix printings can sit in the same deck and on the board at once. 103.2.b.2: 'Cards have different names even if they represent the same character', with the worked example of 3 Yasuo, Remorseful beside 3 Yasuo, Windrider. So 3 + 3 copies, and nothing pairs them off.
• One of them is the Chosen Champion. 103.2.a.2 asks for 'a champion unit with a champion tag that matches the tag on your Champion Legend' and Voidreaver's tag is Kha'Zix; neither card is signature: true, so 103.2.d.3 does not exclude them. The entry puts the cheaper faucet (UNL-143, E4) in the zone.

Prerequisites

• 'An enemy unit is alone here' IS AN OWN-SIDE MEASUREMENT, AND THE POOL SAYS SO. Two cards print the reminder for the same word: SFD-036 Lonely Poro, '(I'm alone if there are no other friendly units here.)', and UNL-210 Forbidding Waste, '(It's alone if there are no other friendly units here.)'. So the clause means the OPPONENT has exactly one unit at this battlefield; your own garrison is unrestricted. No reading was needed.
• THE CONDITION IS CHECKED ONCE, AT THE DESIGNATION, AND NOWHERE ELSE. 383.4.e.2.b: 'If the trigger condition contains other requirements besides attacking and if those requirements are not fulfilled when the unit gains the Attacker designation, it will not trigger in that combat.' The designation is handed out at 464.2.c.3. So the opponent cannot repair the lone-enemy clause afterwards, and neither can you — and 383.4.e.2.a ('only have their condition checked once per combat, despite a Unit being able to gain and lose the Attacker designation multiple times') closes any re-attack in the same combat.
• THE REMOVAL IS RIOT'S OWN WORKED EXAMPLE. UNL-119's second sentence is the wording of Yasuo, Remorseful, which the Core Rules use three times under 359.3.f. Two consequences the entry stands on: 359.3.f.2 reads the Might AT EXECUTION ('it will deal damage equal to his current Might of 5'), so a Voidreaver Buff raises it to 6 and a -Might lowers it; and the same paragraph's first example gives the opponent a printed out — move UNL-119 home in reaction and 'here' is no longer the combat battlefield, so the trigger mistargets. 359.3.f.4 adds that a control steal does NOT blank it.
• THE BUFF IS EXACTLY +1 MIGHT, ONCE. 703: 'Each Buff individually contributes +1 Might to a Unit.' 702.3: 'There can only be one Buff on a Unit at a time', and 702.3.a says a second is simply not placed — UNL-102 Crowd Favorite prints that rule on a card ('Give me a +1 Might buff if I don't have one'). 705 strips it if the unit leaves play, and 705.1 strips it even in the Champion Zone. Per the #106 rule the product of a repeatable buffer is min(triggers, new unbuffed bodies); here the trigger side is 1 per turn, so Voidreaver is the bound, not the board.
• VOIDREAVER IS ONE ACTIVATION A TURN, AND ONLY IN THE MAIN PHASE. Both paid lines carry an exhaust and there is one exhaust state on one object, so the [Buff] and the Move are alternatives; 315.1.b readies him next Awaken (107.4.c makes a legend such a Game Object). Neither line carries [Reaction], and 813.1.c.2 defines Reaction on an Activated Ability as 'This can be activated during Closed States on any player's turn' — without it, Main Phase only (316.5.b). SO THE BUFF CANNOT ANSWER THE ATTACK TRIGGER: place it before the unit moves in.
• WHAT THE BUFF BUYS, TO THE DIGIT. 465.2.c sums Might and 465.2.c.3 forces lethal onto one body in full. UNL-143 at 4+2 = 6 kills a lone defender of Might 5 or less and survives; at Might 6 both die and 466.3.d is No Result, so Voidreaver banks nothing. Carrying a Buff it is 7 and beats a lone Might 6. That single point is the difference between a won combat and a trade. 466.1.a.1 heals all units in the Combat Cleanup, so marked damage does not carry.
• TWO COMBATS IN ONE MAIN PHASE, AND THE RULE IS 461.1, NOT 429.2. 461.1: 'If more than one Battlefield has Units controlled by opposing players at it at the same time, the Turn Player decides which Combat to resolve first.' The one-at-a-time route is 316.5 ('The Main Phase has no defined structure') with 316.6 ('one or more structured phases may occur'). Either way UNL-143's XP is banked before UNL-119 gains the Attacker designation.
• VOIDREAVER'S SECOND LINE IS A MOVE, NOT A RECALL, AND IT COSTS YOU THE BATTLEFIELD. The card says 'Move an exhausted friendly unit from a battlefield to its base'; 455 defines a Recall as a relocation to the Base 'without it being a Move', so this is not one and the 808.1.d.1 Deathknell trap does not arise. 420.3.a puts the exhaust cost only on the STANDARD Move, which is why an already-exhausted body is a legal subject. The price is 323.6: if it was your last unit there you lose Control of that battlefield in the same Cleanup.
• IT IS NOT INFINITE AND NOT CHAIN, AND THE REASON IS NOT THAT XP IS A RATCHET. 824.1.d makes a [Level N] ability Inactive 'as soon as the controlling player has less than [N] XP', and 730.2 says spending reduces the marked value, so XP is a balance you walk down yourself — already registered on wuju-master-blood-rose-level. The reason this lens yields ENGINE is simpler: NOTHING IN THE POOL CONVERTS XP TO POINTS. The combats and the battlefields are bounded too (485.4, 'Battlefield Count: 2').
• THE LEVEL CARDS THIS ENGINE FIGHTS, IN ITS OWN DOMAINS. A full [Level sweep of the pool finds no Chaos entry and three in Body: UNL-094 Gemhand Hunter ([Level 6] +1 Might, continuous), UNL-098 Targonian Visionary ([Level 11] +4 Might, continuous) and UNL-091 Concentrate ([Level 6]/[Level 11] discount, read once at 356). Each UNL-119 removal costs 3 XP, so a board leaning on a continuous [Level 6] wants 9+ banked before firing.
• THE REMOVAL TARGETS. 'An enemy unit here' is chosen by the controller, so 355.10.d (programmatically selected, not chosen) does not apply and 809.1.c / 809.1.d charge a [Deflect] body the extra Power.
• IF THE CHOSEN CHAMPION DIES IT DOES NOT COME BACK. 108.3.c: 'The Chosen Champion cannot be returned to this zone by normal means.' The one exception in the whole pool is OGN-281 Hallowed Tomb, which is Colorless and so legal here, and 108.3.c.1 lets it fire only while the zone is empty. 485.4.a and 103.4.c mean you bring three differently-named battlefields and one is used, so it is not a plan.
• UNL-143 ALSO APPEARS IN vex-star-crossed-rebound-stun, as the payoff of a mono-Chaos bounce line. That entry needs a Chaos legend and this one needs Voidreaver specifically, so the two cannot share a deck; the card is simply good in both.
• UNL-129 VICIOUS SNAPJAWS IS THE POOL'S ONLY CHAOS DEATH TRIGGER, AND THIS IS THE ONLY CATALOGUED SHELL THAT CAN RUN IT (issue #146's snapjaws-xp-mill candidate, walked 2026-09-06 and REFUTED as an entry of its own). Text verbatim: 'UNL-129 | Vicious Snapjaws | Unit | Chaos | E5 M5 | When another friendly unit dies, gain 1 XP.' IT FIRES PER DEATH, NOT ONCE A TURN: 383.3.e governs abilities that trigger "once each turn," or "N times each turn" and 383.3.e.1 caps only those; Snapjaws prints no such clause, and the pool's two cards that do are worded the other way (OGN-118 Wraith of Echoes and UNL-174 Shard of Undoing both open 'The first time a friendly unit dies'). It names no location either, unlike UNL-145 Pyke, Returned's 'while I'm at a battlefield', so it pays from your base. WHY IT IS NOT ITS OWN ENTRY. #146 hangs it on lux-infinite-energy, which kills OGN-110 Ekko, Recurrent every pass as UNL-173 Sacrifice's additional cost — but that entry's legend must cover Mind and Order, a legend has exactly two domains, so 103.1.b.2 fixes the identity at Mind/Order and 103.1.b.3 ('If a card has a single Domain, then that card is permitted in the Domain Identity that corresponds to the same Domain') keeps mono-Chaos Snapjaws out; 103.1.b.1 is the bar. No other catalogued INFINITE is Chaos-legal except pursuer-herald-recruits, which has no death in it and whose OGN-177 is banned in Constructed. AND THE PRODUCT DOES NOT COMPOUND: 733 says 'There is no limit to an amount of XP a player can accrue', but nothing converts XP to points (#116), and the sinks are a bounded step function — eleven cards print a 'Spend N XP' cost and fifteen carry twenty [Level N] clauses, the largest threshold in the pool being UNL-059's [Level 16]. Each sink is capped besides: an exhaust in the cost is one activation a turn (315.1.b), a 'this turn' grant is idempotent, 702.3 / 702.3.a make a second [Buff] on a unit 'not placed instead' so UNL-102's and UNL-162's 2-XP buff is one-shot per body, and 730.2 read with 824.1.d walks your own Level abilities back down on every spend. WHERE IT DOES BELONG IS HERE. Voidreaver fixes this deck at Body/Chaos (103.1.b.2) and 103.1.b.3 admits mono-Chaos UNL-129; it is not banned and is signature: false, so 103.2.d.3 does not touch the Chosen Champion choice. Against this entry's named sink it is a third faucet beside Voidreaver's +1 per combat won and UNL-143's +2 per lone-enemy attack or defence — and the counter-cyclical one, since Voidreaver's income needs the combat WON while Snapjaws pays for the bodies you lose getting there (465.2.c: 'each player assigns an amount of damage equal to their summed Might among the other's Units', so a win still costs bodies). Honest rate: one XP per friendly unit death, at E5 M5. Not added to uses: uses is what the matcher and planDeck price, and this entry's declared income is the two faucets it names.

Steps

1. Voidreaver in the Legend Zone. Kha'Zix, Mutating Horror is the Chosen Champion and starts in the Champion Zone (103.2.a.1); play it from there (108.3.d) for 4 Energy + 1 Chaos Power, to your base or, with [Ambush] (822.1.b), as a Reaction to a battlefield where you already have units.
2. Main Phase: if Voidreaver is ready and you hold 1+ XP, Spend 1 XP and exhaust him to [Buff] the body that will fight. That is his one activation this turn, and it has to happen now — his abilities have no [Reaction] (813.1.c.2), so they cannot answer a trigger later.
3. Standard Move Kha'Zix, Mutating Horror from your base to a battlefield where the opponent has exactly one unit (144.2 exhaust, 144.4.a). The Destination becomes Contested (450), a Combat is staged at the next Cleanup (323.9) and opened (323.13).
4. At 464.2.c.3 it gains the Attacker designation and its trigger's condition is checked there and only there (383.4.e.2.b). The trigger goes on the Combat Chain (464.2.e) and resolves: +2 Might this turn, gain 2 XP.
5. Combat damage: 465.2.c sums Might. At 6 (7 with the Buff) it kills the lone defender and survives. Being the only player with units there is a win under 466.3.a, so Voidreaver's free line adds 1 XP. Bank: 3 XP.
6. 466.5 establishes Control and 466.5.d makes it a Conquer, scoring that battlefield (469.1, 470).
7. Back in the Main Phase (316.6), Standard Move Kha'Zix, Evolving Hunter to the second battlefield's garrison. If both units were moved before either combat, 461.1 lets you resolve the Mutating Horror combat first instead.
8. At 464.2.c.3 the Evolving Hunter gains the Attacker designation; its attack trigger finds the 3 XP already banked. Spend it (730.2) and deal damage equal to its current Might (359.3.f.2) — 5, or 6 if it is the body you buffed — to an enemy unit there.
9. Its [Hunt] (823.1.c.1, X omitted = 1 by 823.1.c.2) pays at the Conquer in 466.5 or at the next Hold in 315.2.b.2: after this attack's spend, in time for the next.

Per iteration

+1 XP per combat won on either side of the table, +2 per lone-enemy Mutating Horror attack or defence, +1 per Evolving Hunter conquer or hold; -3 per 5-or-6 damage removal and -1 or -2 for Voidreaver's single activation

How it ends

engine only — one lone-enemy combat a turn funds one Evolving Hunter removal every turn and change; XP survives between turns (729, 733) so the bank carries, but nothing in the pool turns it into points

Sources

Published elsewhere

• Combo hunt: champion progression (Level/XP/Flow/Champion Zone) — issue #116 (GitHub) 2026-09-06
• Riftbound Core Rules, Last Updated 2026-07-16 (data/Riftbound-Core-Rules-2026-07-16.txt) 2026-07-16
• Hand walk 2026-09-06, the chaos-first units lens (docs/phase0/walks/2026-09-06-chaos-units-lens.md) — the issue #146 link this row used to carry does not discuss this entry or any of its cards, checked end to end 2026-09-09; the WALK does, and it is the provenance this row stands for. 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

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