Combo · ENGINE

Forgotten Library is Karma's only repeatable trigger that costs no card and no deck slot — and 'spent' is what a discount switches off

2 cards · order · verified

Pieces

• Karma, Channeler ×1 OGN-235 · payoff · order

  [Vision] (When you play me, look at the top card of your Main Deck. You may recycle it.) When you recycle one or more cards to your Main Deck, buff a friendly unit. (If it doesn't have a buff, it gets a +1 Might buff. Runes aren't cards.)

• Forgotten Library ×1 UNL-211 · battlefield

  While you control this battlefield, when you play a spell, if you spent 4 Energy or more, [Predict]. (Look at the top card of your Main Deck. You may recycle it.)

Payoff

Deck

• Any legend with Order among its two domains (103.1.b.3) — 17 names: Hand of Noxus (OGN-253), Radiant Dawn (OGN-261), Herald of the Arcane (OGN-265), The Boss (OGN-269), Lady of Luminosity - Starter (OGS-021), Might of Demacia - Starter (OGS-023), Void Burrower (SFD-187), Emperor of the Sands (SFD-197), Chem-Baroness (SFD-201), Grand Duelist (SFD-205), Piltover Enforcer (UNL-187), Green Father (UNL-195), Deceiver (UNL-199), Keeper of the Hammer (UNL-203), Eye of Twilight (VEN-147), Matriarch of War (VEN-153), Heart of the Tempest (VEN-155).
• CONTROL of the Library — 190.1 establishes Control through the course of play, and the card says 'While you control this battlefield', so it is switched off until you take it.
• One of your three battlefields is the Library; 485.5 selects one of the three at random.

Run play

• the Library's buff lands before their removal resolves

Prerequisites

• THE ONLY ONE OF KARMA'S THIRTY-FIVE PARTNERS THAT REPEATS FOR FREE. Every other recycler in her matrix row is a card you cast or a permanent you paid for; the Library is in the battlefield zone, which 103.4.c and Tournament Rules 402.1 keep out of the Main Deck entirely, and it fires on an event an Order deck causes anyway — playing a spell.
• 'IF YOU SPENT 4 OR MORE' READS THE RUNE POOL, NOT THE CARD, AND A DISCOUNT SWITCHES IT OFF. 166.2 makes players 'add Energy and Power to their Rune Pool in order to be able to spend it to play cards', 203.1 defines paying a cost as performing that action, and 356.4.b lets a discount reduce what the card costs — so a 6-Energy spell discounted to 3 SPENT 3 and does not arm the Library. The mirror is 820.1.c.1, which makes a [Repeat] cost 'an Additional Cost to be paid during the steps of playing the spell': a 2-Energy spell with a 2-Energy [Repeat] plus a 1-Energy rider crosses 4 where the discounted big spell does not. This is the 'spent' half of the split 206 draws for the 'costs' family, and it points the deck at cheap spells with additional costs rather than at expensive ones.
• PREDICT IS A LOOK, AND LOOKING NEVER BURNS OUT. 436.1: 'Predicting a card is the act of looking at a single card from the top of the Main Deck and choosing whether or not to Recycle it.' 431.1.c protects the look ('looks at or Reveals as many as possible, but does not Burn Out') and 436.4.a says it outright for Predict, so the Library is safe in an empty-deck shell where a draw would cost a point (431.1.a, 194.1.d).
• AND THE RECYCLE IS OPTIONAL, WHICH IS THE ENTRY'S ONE REAL TENSION. 'You may recycle it' — keeping a good top card means no recycle, and no recycle means no Karma trigger. The Library is a buff engine only on the turns you do not want what is on top.
• THE PAYOFF IS CAPPED BY 702.3, NOT BY THE TRIGGER COUNT. 'There can only be one Buff on a Unit at a time' (702.3.a: a second is not placed), so the product is min(triggers, NEW UNBUFFED BODIES). Three spells in a turn into a static board buy one buff. The Library scales with how many fresh units you play, not with how many spells you cast — the same shape #106 measured for the Recruit loop.
• The buff is a real 702 counter, not a 'this turn' modifier, so it is permanent and can be SPENT by the pool's buff-spenders (702.2.b) — and it collides with any other buffer aimed at the same body.
• A rune recycle never fires her: her own printed reminder says 'Runes aren't cards' and 161.2.b sends a recycled rune to the Rune Deck rather than the Main Deck, so 164.2.b's '[Recycle this]: [Reaction] — Add [C]' — which every deck does several times a game — is invisible to her.

Steps

1. Bring Forgotten Library as one of your three battlefields (485.5 selects at random) and establish Control of it in play (190.1).
2. Play Karma, Channeler (6 Energy + 1 Order Power). Her [Vision] gives one Predict on arrival, which is itself a possible first trigger.
3. Cast a spell and SPEND 4 or more doing it — count what leaves the Rune Pool, including any [Repeat] cost (820.1.c.1), not the number printed on the card (356.4.b).
4. The Library's trigger fires: [Predict] — look at the top card of your Main Deck (436.1).
5. Choose to recycle it. That is one recycle to your Main Deck (416.1.a).
6. Karma's trigger fires: buff a friendly unit that does not already have a buff (702.3).

Per iteration

one card recycled to the bottom, one +1 Might buff placed, for no card and no extra Energy

How it ends

engine — one +1 Might buff per expensive spell, bounded by the number of unbuffed bodies rather than by the number of spells (702.3); 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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