Combo · ENGINE

Jayce buys a second activation once a turn, and the ability worth buying twice is the one with a hard cap per use

5 cards · mind · verified

Pieces

• Jayce, Brilliant Inventor ×1 VEN-068 · engine · mind

  When you play me or the first time you play a non-token gear each turn, you may ready something besides me that's exhausted.

• Sky Cruiser ×1 VEN-060 · payoff · mind

  Discard a gear, 1 Energy, Exhaust: Deal 4 to a unit at a battlefield.

• Seal of Insight ×3 OGN-120 · enabler · mind

  Exhaust: [Reaction] — [Add] 1 Mind Power. (Abilities that add resources can't be reacted to.)

Payoff

Deck

• All three cards are mono-Mind, so ANY legend whose two domains include Mind runs the line (103.1.b.1). Nothing here is Signature (103.2.d.2).
• Two gear cards in hand per turn beyond the one you play — the Cruiser's cost discards one per activation, and 203.3 makes an unpayable cost unpayable.

Prerequisites

• WHY THIS PARTNER AND NOT ANOTHER OF THE SEVENTY-SIX. Jayce's rule matches every card in the pool with an exhaust in an ability cost, and the project has already established the filter: a multiplier is worth nothing on an effect with no per-execution cap — which is why the rule itself excludes SFD-117 Ancient Henge and SFD-083 Hextech Anomaly, both 'Pay any amount'. Sky Cruiser is the opposite shape: 'Deal 4' is fixed per use, so the second activation is worth a second full 4. That is the whole basis on which a partner earns an entry in this family.
• THE ORDER IS FIXED BY 415.1.b. 'A Unit that is already Ready cannot be Readied again', and 415.1.c: 'If a Unit is instructed to be Readied while it is already Ready, nothing additional happens.' Jayce's trigger fires when the gear is PLAYED, so the Cruiser has to be exhausted before that: activate first, play the gear second, activate again. Playing the gear first wastes the trigger entirely.
• AND IT IS THE FIRST GEAR ONLY. 'The first time you play a non-token gear each turn' is an ordinal trigger; 383.1.b covers 'the [Nth] time' and 383.3.e.1 covers 'N times each turn' — either way a second gear the same turn pays nothing. So the enabler wants to be the CHEAPEST gear in the domain, not the best one, and OGN-120 Seal of Insight at 0 Energy plus a Mind rune is it — and it refunds that rune the moment it is on the board, since its own ability is '[Add] 1 Mind Power'.
• THE ARITHMETIC, WITH THE QUANTITIES DECLARED. Per turn: activate the Cruiser (discard a gear, 1 Energy, exhaust) for 4 damage; play Seal of Insight (0 Energy + 1 Mind Power) and take Jayce's ready on the Cruiser; activate again (discard a gear, 1 Energy, exhaust) for 4 more. TOTAL 8 damage for 2 Energy, 1 Power, two gear discarded and one gear played — every turn, with no card drawn and nothing else on the board. Eight damage kills all but a handful of bodies in the pool outright (143.2.a: 'nonzero damage marked on it equalling or exceeding its Might').
• THE DISCARD IS A COST, WHICH CUTS BOTH WAYS. 203.3 makes an action a cost asks for and cannot perform unpayable, so two activations need two gear in hand — this deck is built with gear as ammunition, and 422.1.b makes a 'When I am discarded' trigger execute AFTER the discard, from the trash, so gear with such text is free value here rather than a loss. Conversely a hand with one gear fires once, and the entry says so instead of assuming the second.
• IT REACHES A UNIT AT A BATTLEFIELD, NOT A BASE. 'Deal 4 to a unit at a battlefield' is the ordinary restriction; the base is out of range. That is the one thing this package cannot do and it is why it sits beside, not instead of, the base-reaching removal the catalogue already holds.
• WHAT REFUTES IT. (a) Jayce is E6 + 1 Power and the Cruiser E4 + 1 Power, so the package is two top-end bodies before it does anything. (b) Both enter exhausted (143.4), so the engine starts the turn after the second lands. (c) Jayce's trigger is a 'you may', so nothing is forced — but it is also once per turn, and no amount of extra gear widens it.

Steps

1. Earlier turns: play Jayce, Brilliant Inventor (E6 + 1 Mind Power) and Sky Cruiser (E4 + 1 Mind Power). Each enters exhausted (143.4) and is readied in your Awakening (315.1.b).
2. Main Phase. Activate Sky Cruiser: discard a gear from hand, pay 1 Energy, exhaust him. Deal 4 to a unit at a battlefield.
3. Play Seal of Insight (0 Energy + 1 Mind Power) — the first non-token gear you have played this turn. Jayce's trigger fires.
4. Ready something besides Jayce that is exhausted: the Sky Cruiser (415.1).
5. Activate him again: discard a second gear, pay 1 Energy, exhaust. Deal 4 more.
6. Exhaust the Seal at any Open State for 1 Mind Power back ('[Reaction] — [Add]'), which pays for its own play.

Per iteration

8 damage a turn for 2 Energy and a Power that the enabler refunds, at the price of two gear out of hand

How it ends

engine only — Jayce's ready is once per turn whatever else you play, and 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

• Synergy rule jayce-readies-exhaust-abilities (data/synergies.json) 2026-09-06
• Hand walk 2026-09-07 (docs/phase0/walks/2026-09-07-rules-second-pass.md), issue #170 2026-09-07 record

Walked against Core Rules 2026-07-16

Match a deck list against the whole catalogue