Combo · ENGINE

359.3.e.11 - the discard on Undercover Agent is EFFECT text, so an empty hand ignores it and the Deathknell is a clean draw 2, doubled by Karthus into four cards off one death

6 cards · chaos + order · verified

Pieces

Undercover Agent ×3 OGN-178 · engine · chaos
[Deathknell] — Discard 2, then draw 2. (When I die, get the effect.)
Karthus, Eternal ×3 OGN-236 · engine · order
Your [Deathknell] effects trigger an additional time.

Payoff

Repeatable card advantage

Deck

Undercover Agent is mono-Chaos and Karthus, Eternal is mono-Order, so 103.1.b.1 forces a legend carrying BOTH. The census run against data/cards.json on 2026-09-09 returns exactly ONE name for Chaos+Order: Heart of the Tempest (VEN-155 / VEN-197). This is a one-legend line and there is no second shell.
Neither card is Signature (data/cards.json, signature=false on both) and neither appears in data/legality.json in either format - checked 2026-09-09.

Prerequisites

359.3.e.11 WAS UNCITED AND ITS WORKED EXAMPLE IS THIS CARD'S SENTENCE. The rule: 'Instructions that can be partially followed are followed as much as possible and ignored otherwise.' Its EXAMPLE: 'A player plays a spell that says "Discard 2, then draw 2." If their hand is empty, the instruction to discard 2 will be ignored. They'll still draw 2. If they had 1 card in hand, they would discard it and draw 2.' So the pool's own reading - that a discard clause is a price - is wrong here.
AND 422.4 NAMES THE CARD OUTRIGHT: 'When Discarding is part of an effect, then a player must Discard as many cards as possible from their hand. If instructed to discard more cards than they have in their hand, further discard instructions are ignored.' Its EXAMPLE: 'Undercover Agent has the ability "[Deathknell][>] Discard 2, then draw 2. (When I die, get the effect.)" If Undercover Agent's controller has 2 or more cards in hand, they must discard 2. If they have 1 card in hand, they discard 1, and the rest of the discard instruction is ignored. If they have no cards in hand, the entire discard instruction is ignored. Regardless of how many cards they discard, they then draw 2.'
THE COST-VERSUS-EFFECT LINE IS WHAT MAKES IT WORK, AND IT IS ONE PARAGRAPH AWAY. 422.3: 'When Discarding is listed as a Cost, then the Action must be able to be completed for the cost to be paid.' If this discard were a cost, 422.3 with 203.3 would refuse the whole ability on an empty hand. It is not: it sits after the [Deathknell] marker, which 808.1.c makes 'functionally short for "When I die, [Effect]."' Read the marker before pricing any discard.
NOR IS THE DRAW LINKED TO THE DISCARD. 359.3.e.14.a: 'In order for a later linked instruction to execute, its earlier linked instruction must have executed. If the earlier linked instruction is ignored for any reason, the later linked instruction will also be ignored.' Two instructions are linked only when the later one references the earlier one's objects or actions - 'then draw 2' names nothing the discard touched, which is exactly why 359.3.e.11's example ends 'They'll still draw 2.'
THE ARITHMETIC, BOTH WAYS ROUND. 383.3.d lets the controller order the two simultaneous instances Karthus creates. From an EMPTY hand: instance one ignores the discard entirely and draws 2; instance two now sees two cards, discards them and draws 2. Four cards drawn, two held, two in the trash. From a hand of two or more: four discarded and four drawn, hand size unchanged and four cards of trash fuel. The card is a refill at one end of the game and a trash filler at the other, and 359.3.e.11 is the only reason the first mode exists.
THE SHORTFALL IS THE BODY, NOT THE RULE. A Deathknell fires once per body (808.1.d makes the Trigger the permanent being Killed and sent to the Trash), so 103.2.b caps this at three deaths a game unless a reanimation line brings the Agent back - a lead, not a use of this entry. And 808.1.d.1 erases the whole thing if the Agent's death is replaced by a heal, an exhaust, a recall or a banish, which is a real risk on a body you intend to lose.
BURN OUT IS THE PRICE OF THE DOUBLE. 431.1 makes Burning Out an action 'a player must perform if they attempt to move one or more cards from their Main Deck to any other zone in excess of the number of cards remaining in their Main Deck', and Karthus turns two draws into four. In a normal 39-card shell that is nothing; in a late-game or empty-deck shell it is a point for the opponent, so the doubled instance is the one to decline if the deck is short - 383.3.d lets you order them, but neither instance is optional, so the real control is not playing Karthus into an empty deck.

Steps

Play Karthus, Eternal (E3 + 1 Order Power) and Undercover Agent (E5 + 1 Chaos Power) under Heart of the Tempest, the only legend that holds both domains.
Spend the hand before the Agent dies if you want the refill mode; hold cards if you want the trash mode. Nothing has to be committed in advance - the branch is decided by hand size at the moment he dies.
When Undercover Agent dies, 808.1.c fires the Deathknell and Karthus adds a second instance of the same effect. 383.3.d lets you order the two.
First instance, empty hand: 422.4 and 359.3.e.11 ignore the discard instruction entirely, and the draw 2 still executes.
Second instance: the two cards just drawn are now in hand, so the discard executes in full and a second draw 2 follows.
Net from empty: four cards drawn, two in hand and two in the trash, for no cards spent beyond the body that was going to die anyway.

Per iteration

one death converted into four draws, with the discard half free whenever the hand is empty

How it ends

engine - four cards drawn off one death, two of them held and two put in the trash when the hand starts empty; four discarded and four drawn when it does not. Three deaths a game at 103.2.b, at a board cost of E8 + 1 Order Power + 1 Chaos Power for the pair; 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 2026-09-09, issue #187 - uncited Core Rules sub-rules 300-499 2026-09-09 record

How this entry was audited

REFUTE = a refutation pass, with its date and verdict · WOUNDED = the pass found a flaw and the entry was rewritten · BUDGETED = the pass checked the recycle-and-draw ledger · lens = the hunt that proposed it.

359.3.e.11 was cited by nothing in data/combos.json or data/synergies.json before this entry, although 359.3.e.10 and 359.3.e.14.a both were - and 422.4's own worked example names OGN-178 Undercover Agent by name, which is Riot pointing at a pool card. Card text verbatim from data/corpus_flat.txt. The Chaos+Order legend census was RUN against data/cards.json on 2026-09-09 and returns exactly one name; it was not typed from memory. No unruled reading.

Walked against Core Rules 2026-07-16

Match a deck list against the whole catalogue