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Towards a comprehensive rulebook: proposed errata & rules changes (partial, draft, request for feedback)

There’s a handful of things written in the Codex rulebook or on cards that have either been directly overturned by @Sirlin or @Sharpobject (because they would lead to unintended behavior), or haven’t and do lead to unintended behavior. A larger number of cards and interactions are simply under-defined, and require the creation of specific rules.

This is a draft of a proposal to errata a handful of cards and change and define a few under-the-hood game mechanics. The approach is to a) make things work as intended while b) simplifying interactions and c) reducing or eliminating rules arcana. The ultimate goal is to produce a comprehensive rules document, separating and extracting the rules from the rulings in the “rulings spreadsheet”.

My particular targets are the different categories of “effect speeds” that have been created to make Smoker, Graveyard, Reteller of Truths, and Second Chances work, and the long list of state-based actions found only here – I consider these arcana and think these things can be holistically unified with a few changes.

This is not a complete or finished proposal. In particular I need to do more reading of rulings on the various steps involved in attacking, as well as copying and “layers”. (It also has nothing like a consistent style guide.)

None of this should be taken as a criticism of the existing rules, rulings, or card wordings. Card space is finite, and over the course of three thousand posts any series of ad-hoc rulings is going to become a little messy. I’ve held a physical volume of the Magic: The Gathering comprehensive rules, and that much mass is not something to strive for.

Simple card errata:

Crypt Crawler: change activated ability to
{1} --> Ground a flying unit, hero, or building until end of turn. (It loses flying and cannot fly this turn.)

This clarifies that the Crawler beats passive abilities like Wandering Mimic and Fairy Dragon – they don’t immediately lift off again due to “state based effects”.

Gargoyle: change card text to
Indestructible, but can’t attack or patrol.
{1} --> Until your next upkeep, Gargoyle gains flying and +3 ATK, and loses “Indestructible, but can’t attack or patrol.” Once per turn.

The “can’t beats can” rule in the rulebook makes Gargoyle unable to ever attack, as written. If you flip that rule, Entangling Vines can’t grapple a patrolling Gargoyle, unless you make another rule about why Gargoyle’s “can attack and patrol” beats one instance of “can’t attack or patrol” but not another.

Sacrifice the Weak: change card text to
Each player sacrifices their weakest sacrificable unit. (The lowest tech unit with the least ATK. You choose if there’s a tie for least ATK. Indestructible units can’t be sacrificed.)

Hooded Executioner: change “destroy” clause to
…destroy each opponent’s weakest non-indestructible unit.

Death Rites: change “destroy” clause to
…destroy one of an opponent’s lowest-tech non-indestructible units.

As written, the “can’t beats can” rule means that all three cards would attempt to destroy Hardened Mox or a gilded Gilded Glaxx, which then don’t actually die (although it would sideline the Mox). Sacrifice the Weak would require no sacrifice at all if your weakest unit is a Pestering Haunt! The ruling here is that these effects (and Obliterate) should skip indestructible units and a gilded Gilded Glaxx; this errata makes that happen. Except that Glaxx isn’t indestructible…

Gilded Glaxx: change card text to
While you have gold, Gilded Glaxx can’t leave play until it is dealt lethal combat damage, can’t be sacrificed, and is skipped when calculating the weakest or lowest-tech unit to destroy due to an effect such as Obliterate. (Any amount of combat damage from a Deathtouch unit or while Glaxx has at least as much damage as health is lethal combat damage, even to armor.)

…so we put the skipping property directly on Glaxx, as part of the ability.

I like the “until it is dealt” wording because it clarifies that the time of taking combat combat damage is what kills Glaxx; you aren’t tracking which damage chits came from combat and which chits were from burn spells, killing Glaxx when the combat chits are sufficient to kill it, or if at least one of them is from combat and its health is lowered, etc. Putting the “until” first also tells the opponent exactly what they need to do to kill it before their eyes glaze over from reading excessive card text.

Damage to armor while Glaxx has otherwise fatal damage on it does overturn an existing ruling; I’m reversing it to be consistent with Deathtouch and the flavor that the unfortunate thing about plutanium plating is that it scratches easily.

Prynn Pasternaak: change midband ability to
4-6: Fading removes last time rune: Opponents skip their next draw/discard step.

Per @Sirlin, this is the intended behavior. However, the sacrifice portion of the fading mechanic doesn’t care how or why you lost the last time rune, so the distinction needs to be on the card.

Wandering Mimic: change the first clause to
As long as a another non-Shapeshifter unit or hero with flying is in play, …

Rules and flavor-wise, there isn’t really a problem with two Mimics granting each other flying, and as originally written, that’s how it works. It’s a stable loop; it would only be a problem if Mimic said “As long as no other unit or hero with flying is in play…”. Gameplay-wise, however, it requires extra bookkeeping and takes away counterplay for the opponent, as once you have two Mimics out they can’t remove an ability by getting rid of the thing that originally had the ability. Sirlin has ruled that Mimics don’t grant each other abilities, so we update the card text to reflect that.

Simple keyword/rules errata:

+1/+1 and -1/-1 runes: formalize annihilation bit ("+1/+1 and -1/-1 runes destroy each other if they would go on the same object.") to
If you would put a +1/+1 rune onto something that already has a -1/-1 rune (or vice versa), remove the existing opposite rune from it instead. If you’re placing multiple +1/+1 runes, each removes one -1/-1 rune until there are no -1/-1 runes, then put the remaining +1/+1 runes on normally.

Noting this non-errata because the original wording is cleaner than the interpretation that +1/+1 and -1/-1 runes coexist until state-based effects are checked. It’s better to prevent “illegal” states from happening altogether than to rely on a state-based mechanism to clean it up; it means the rest of the rules can assume the game isn’t in an illegal state, and you don’t need to have a complex mechanism with different priorities for “fixing” different things. It may not seem like a big deal here, but it will when we get to the Legend Rule.

Remove a (kind) rune --> means that to use the ability, you pay the cost by removing a rune from the unit or hero with the ability.

This is the official ruling, so it should go into the eventual rulebook.

Lookout: define as
It costs 1g more for an opponent to :target: a unit or hero patrolling in the Lookout slot, exactly as if it had Resist 1 (or Resist X+1 if it already had Resist X).

Midori’s midband is supposed to apply to vanilla units in any patrol zone, so it’s important that Lookout not actually grant any abilities. Scavenger and Technician don’t grant a Dies: trigger, either, but it isn’t stated that they do.

Legendary Cards: expand to
If a unit, building, or anything else is marked as “Legendary”, then you can only have one copy of it om play under your control. You can never, ever have two of a given Legendary in play, even if some other rule or card implies you can. (You can tech both copies from your codex to increase your odds of drawing one, or to have a second copy ready play when the first dies; you just can’t have both in play at the same time.)

If you have a Legendary thing in play, you can’t play another copy of it from your hand. (not strictly necessary but might more intuitive?)

If you have a Legendary thing in play and you would put another of the same Legendary into play, the card goes to its owner’s discard instead. This happens even if the existing Legendary is currently polymorphed into a squirrel or copying a regular unit or something.

If you would put two copies of the same Legendary into play at the same time, put only one of them into play and put the other into its owner’s discard instead.

If you would gain control of an existing Legendary, but already control one with that name, put it in its owner’s discard instead of gaining control of it.

You can’t make a units into a copy of a Legendary unit that unit’s controller already controls. Instead of being copied, the copy effect doesn’t happen.

The goal here is to avoid having a state-based Legend Rule which allows two of a given Legendary to exist momentarily, and then having to keep track of a “has identity while under your control” timestamp, or allowing players to put a very briefly put a second Jade Fox into play for more ninja tokens. In my experience the “cannot play a second copy” rule would be more intuitive and easier to explain to most people than “you technically can do this thing but it won’t end how you want”; on the other hand, it’s one more rule than strictly necessary. I think it comes down to whether players think about it as having to remember that you technically can play a second copy, it just goes to the discard, or as having to remember that you technically can’t even play the second copy.

Limit: X means that a card can’t make you have more than X of the appropriate kind of unit token under your control: If an ability on that card says to put another token into play and you already have the maximum permitted, it doesn’t happen. It doesn’t matter if the card has more than one effect that can make the tokens; the limit is for the whole card, not a particular ability. Like with Legendary cards, creature tokens that are squirrels or copying another thing still count against the limit.

This doesn’t prevent something else from exceeding the limit on that kind of creature token. For example, if your Sirius Quince casts Manufactured Truth to make his second Mirror Illusion token into a copy of one of your Stinger tokens, you might end up with 6 Stingers and only one Hive. In this case, Hive can not create any more Stinger tokens until there are fewer than 5 under your control – and Quince can’t create any more Mirror Illusions, either.

Everyone Dies (but they don’t all go to the same place)

Zone Transfer Modification

This is an interpretation of the original rules that reduces the number of state-based effects that need to be checked, and allows Graveyard, Second Chances, and Reteller of Truths to be cleanly errata’d to avoid having to create special timing rules for them. The problem arises when Graveyard is interpreted a “pull out of discard” triggered effect that goes onto a queue of events. Suppose you have a Graveyard, a Gorgon, and no cards in your deck. It’s your opponent’s turn, and they kill your Gorgon. If the Graveyard ability needs to go onto an event queue, then they can put Gorgon’s Dies: Draw a Card event onto the queue first, which will cause your discard to be shuffled, Gorgon included. Now we can’t bury Gorgon in the Graveyard, because it’s probably in your deck but maybe in your hand.

Graveyard: change “Whenever your non-token units die, bury them here.” to
Your non-token units that die are buried here.

This is what I’m going to call a zone transfer modification effect. Normally, when non-token units die, they go to the discard. Graveyard changes that game rule to put them under Graveyard instead – no need for them to be pulled out of the discard.

We can use the same concept to deal with other things that aren’t supposed to be in your discard. The referenced “state-based actions” code has a check to pull heros out of the discard into the command zone and delete tokens in odd places. We can eliminate that entirely:


Cards and other Codex entities can be in many different “zones”: in play, in a player’s hand, in a deck, in a discard, in a Codex, in the future, in the trash, among others. Various game actions move cards from one zone to another. Some are straightforward – drawing a card moves it from deck to hand, teching a card moves it from codex to discard, and reshuffling moves the entire discard into the deck.

When you use a card to make a worker, the card is removed from the game. There is no “worker zone” – a player has some quantity of workers which can be incremented or decremented, but the removed cards cease to exist as far as the game is concerned.

When you play a card, it leaves whatever zone you are playing it from (normally, your hand).
Cards with Forecast go into the future.
Units, buildings, upgrades, and ongoing spells are put into play.
Other spells resolve; resolving a spell puts it into the discard.
Heroes also go into play, but are always played from the command zone.
Tech buildings and add-ons aren’t “played”, per se; when construction is complete at end of turn, they are created and put into play.

When something dies, it leaves play. Where exactly it goes – if anywhere – depends on what it is:
Heroes return to the owner’s command zone.
Unit cards (i.e., not tokens), building cards, and upgrades, are put into the owner’s discard, face down.
Tech buildings, add-ons, and unit tokens leave play and cease to exist. (but you can still create new ones.)

Some spells and abilities can move cards from one zone to another, redirect cards heading into or out of one zone into a different one, or even create their own special zones altogether. If two abilities would try to redirect a card to different zones, the active player chooses which one takes effect.

Heroes that leave play always go to the command zone, and non-card entities (unit tokens, tech buildings, add-ons) that leave play always cease to exist, even if a card says to put them somewhere else. They can never be in the discard, in a players hand, or even in the trash.

(something something lack of continuity when a unit leaves play and comes back again)

Zone Transfer Errata

Graveyard: change “Whenever your non-token units die, bury them here.” to
Your non-token units that die are buried here.

Jail: add a line brake between “…instead of arriving.” and “When a unit enters jail…”

Not strictly necessary, but makes it more clear that only the second half of Jail is a triggered ability.

Noting that because the game rules have Forecast units going into the future when played, rather than Forecast itself being a zone transfer modification ability, the “conflicting redirect” rule doesn’t apply; Forecast units never go to jail, consistent with current rulings.

Reteller of Tales: change card text to
The first two of your non-token illusions (including this one) that die each turn return to their owners’ hands.

Reteller doesn’t need errata – the original text still works, and was never templated as a triggered ability – this phrasing just makes it less similar to triggered abilities’ “when…, then…” templating.

Second Chances: change card text to
Each turn, the next non-token unit of yours that leaves play from something other than combat damage is put on Second Chances. (Choose randomly if multiple leave at once.)

When a unit is put on Second Chances, return it to play.

Second Chances is now templated the same way as Jail, with one zone transfer modification ability and one triggered ability. The important consequence of this is that it is no longer able to put things into play as a “fast trigger” – they are put onto Second Chances immediately, and are returned to play at a regular time.

In progress: Smoker, Illusions, and Resist (requires formalizing steps & timings for choosing targets and paying costs), Savior Monk (prevention effects cannot work on a FIFO queue), Stalking Tiger vs. Steam Tank + Behind the Ferns (they have stealth at opposite times relative to selecting defender), and the general process of declaring an attack and choosing a defender (which may have relevance for Setsuki, Morningstar Pass, and Obliterate).


I like it! Small typo, the bit about Jail should say “line break” rather than “line brake.” That said, all of the changes you’ve made make sense, and while I don’t expect this to officially be used I wish it would!

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Hi, this is great!

Some parts of the proposed legendary rule differ from my planned rule for digital codex, and I don’t think the case where you control two copies of a legendary unit because of copy effects expiring is handled.

The example in Limit: X is confusing because copy effects don’t change how many of a unit you have for the purpose of Limit: X. A way to actually exceed the limit on the number of Stingers is to kidnap your opponent’s Hive, make some Stingers, and then give it back. If you also have a Hive you own, you can end up with 1 Hive and 10 Stingers this way.

Prynn got a timing change that has no actual impact on the game, which is of course fine.

If I were to errata a bunch of cards, I would maybe errata Hotter Fire to clear up questions about Sparkshot and give Stalking Tiger and Wight something like “Can attack X kind of thing as though it had Y.” in addition to actually getting Y while attacking that sort of thing.