Effect-Copying Cards: "This Effect Becomes That Card's Effect"

Some cards do not have their own payload — they borrow another card's effect. Serial Spell copies one of your Normal Spells; Transaction Rollback copies a Normal Trap from a GY. They share one rule set, distinct from cards that merely "activate" a copy.

The shared principle: you copy the effect, never the cost, and you still owe the copied card's own activation procedure and game-state conditions.

What carries over and what does not

When card text says the copying card's effect "becomes" the other card's effect:

• Copied: the effect (what resolves), including its activation procedure — targeting, choosing an option, declaring an attacker, etc.
• Not copied: the cost of the original card. You pay the copier's own cost instead.
• Ignored on the original: "You can only activate 1 ... per turn" and "... once per turn" limits. The copy is a fresh, separate activation, so OPT/highlander text on the copied card does not block it. (See Highlander Clause.)
• Still required — for the Serial Spell / Transaction Rollback templates: the copied card's activation conditions must be met at the moment you activate the copier. Copying a trap that needs an attacking monster (Dimensional Prison) means you must activate during a declared attack; copying one that needs a Summon (Torrential Tribute) means a monster must have just been Summoned. This is not universal — see the Witchcrafter Genni exception below before assuming it transfers to every "becomes that card's effect" template.

Serial Spell

"Activate only when you activate one of your Normal Spell Cards. Discard all the cards in your hand to the Graveyard. The effect of this card becomes the same as the Normal Spell Card."

• Discarding the whole hand is Serial Spell's cost — you do not re-pay the copied Spell's cost (chaining to Delinquent Duo does not cost another 1000 LP).
• It chains to a Normal Spell you activated, so that Spell was already legally activated; Serial Spell then resolves a second copy of its effect — even for "only 1 per turn" cards like Instant Fusion.
• Serial Spell is not the copied card and does not stay on the field, so "while this card is face-up" / "remains on the field" riders of the copied Spell do nothing.

Serial Spell + Triple Tactics Talent

Triple Tactics Talent needs "your opponent has activated a monster effect during your Main Phase this turn." Because Serial Spell chains to your already-legal Triple Tactics Talent activation, that condition is satisfied for the original. Serial Spell's resolution then runs a second "Activate 1 of these effects" — you choose again at resolution, so the copy can draw 2 even if the original took control. The copy is a separate effect, so the once-per-turn on Triple Tactics Talent does not stop it.

Transaction Rollback

"Pay half your LP, then target 1 Normal Trap in your opponent's GY, except 'Transaction Rollback'; this effect becomes that card's activation effect. You can banish this card from your GY and pay half your LP, then target 1 Normal Trap in your GY ... You can only use 1 'Transaction Rollback' effect per turn, and only once that turn."

• Targeting is part of the activation procedure, not a cost. When you copy Compulsory Evacuation Device, you activate Transaction Rollback by targeting the Compulsory Evacuation Device in the GY, then immediately target a monster for the copied Compulsory's own activation procedure. The opponent may respond as usual.
• You cannot copy a trap whose payload relies on a value produced by its own cost. Burst Breath Tributes a Dragon as a cost to then destroy monsters by that Dragon's ATK; Transaction Rollback skips the cost, so there is no Tribute and nothing for the destruction to key off — it is not a legal target. Likewise you cannot target Trap Monster cards or traps that equip themselves as part of activation. A declaration or choice bundled into the cost is different: it is part of the activation procedure and carries into the copy (you make it again), so a cost-bundled-declaration trap like Eradicator Epidemic Virus can be copyable — but that case is contested and is an ask-the-Head-Judge call. See Transaction Rollback contested copies.
• The copied trap's activation conditions must be met when you activate Transaction Rollback (e.g. copying Torrential Tribute requires a monster to have just been Summoned).
• Resolution check: at resolution, if the targeted trap is still in the GY, apply its activation-effect resolution; if it left the GY, the copied effect is not applied.

Witchcrafter Genni / Witchcrafter Pupils — same-looking template, opposite ruling on conditions

Serial Spell and Transaction Rollback both need the copied card's own activation conditions met. Witchcrafter Genni and Witchcrafter Pupils use textually similar "becomes that card's effect" wording but are officially ruled the opposite way: the copied Spell's own activation conditions are ignored.

Witchcrafter Genni — "... You can banish this card and 1 'Witchcrafter' Spell from your GY; this effect becomes that Spell's effect when that card is activated. You can only use each effect of 'Witchcrafter Genni' once per turn."

Witchcrafter Pupils — "During the Main or Battle Phase (Quick Effect): You can activate 1 of these effects; ● Add 1 'Witchcrafter' Spell from your Deck to your hand. ● Reveal 1 'Witchcrafter' Normal or Quick-Play Spell in your hand; apply that Spell's activation effect. ..."

Official Q&A (db.ygoresources.com qa/24128): "When you apply a Spell Card's effect due to [Witchcrafter Genni]'s 2nd effect, or due to [Witchcrafter Pupils]'s 2nd bulleted (●) effect, any conditions on activating the Spell Card that are listed on that card are not considered."

Concretely: Verre Magic - Lacrima of Light has a colon-gated condition — "● If you control a 'Magistus' or 'Witchcrafter' monster: Send 1 Spellcaster monster or 1 Spell from your Deck to the GY." That colon-gated clause is a real activation condition under PSCT / Conditional Clauses vs. Activation Conditions — not a mere descriptive clause. Yet when Witchcrafter Genni or Witchcrafter Pupils copies it, you do not need to control a "Magistus" or "Witchcrafter" monster; the condition is waived.

The lesson: do not assume every "this effect becomes that card's effect" copier behaves like Transaction Rollback just because the wording looks similar. Konami has explicitly ruled this both ways for textually similar templates — Transaction Rollback requires the copied card's listed conditions; Genni/Pupils do not. Check the specific card's official ruling rather than generalizing the principle across copier cards.

Judge calls to watch for

• Copy the effect, not the cost; the copier pays its own cost.
• The copied card's activation conditions are checked when the copier is activated for the Serial Spell / Transaction Rollback templates — but not for Witchcrafter Genni / Witchcrafter Pupils (qa/24128), even though the wording looks similar. Confirm the specific copier's official ruling before assuming either way.
• Its once-per-turn / "only 1 per turn" limits are ignored on the copied card regardless of template.
• "Targeting" and "choose an option" are activation-procedure steps that carry into the copy.
• Reject targets whose effect depends on a skipped cost, are Trap Monsters, or equip themselves on activation.
• The copier is not the original card — "while face-up / remains on field" riders of the original do nothing for Serial Spell.

Sources

• Serial Spell rulings (Yugipedia/Fandom Card Rulings)
• Transaction Rollback official Q&A via Konami Neuron DB cid=19049 / db.ygoresources.com/card#19049
• r/Yugioh101 Compulsory vs Burst Breath example
• Triple Tactics Talent cid=15296
• Witchcrafter Genni / Witchcrafter Pupils activation conditions waived when copying a Spell's effect: db.ygoresources.com/data/qa/24128 (also qa/22484); card text via YGOPRODeck API (Witchcrafter Genni, Witchcrafter Pupils, Verre Magic - Lacrima of Light).