Considering the problems in answering this question, I feel like there is a contradiction between rules 720.3 and 720.5:

720.3. Sometimes a loop can be fragmented, meaning that each player involved in the loop performs an independent action that results in the same game state being reached multiple times. If that happens, the active player (or, if the active player is not involved in the loop, the first player in turn order who is involved) must then make a different game choice so the loop does not continue.

720.5. No player can be forced to perform an action that would end a loop other than actions called for by objects involved in the loop.

Assume the same scenario as in the original question, Lethal Vapors and Solemnity are on the battlefield, and an undying or persist creature enters the battlefield. Assume further that the active player has only 2 possible game choices, those choices being "passing priority" and "activate Lethal Vapor's active ability".

Note that "passing priority" is a game choice:

720.1. When playing a game, players typically make use of mutually understood shortcuts rather than explicitly identifying each game choice (either taking an action or passing priority) a player makes.

Now, if all players keep passing when they receive priority between Lethal Vapor triggers, the game enters a loop and a draw. However, 720.3 clearly says that in this case, the active player must make a different choice, i.e. other than passing priority. The only remaining choice is activating Lethal Vapor's ability. That, however, might violate 720.5, because the game rules force the active player to end the loop.

So my question is, is there a possible contradiction between 720.3 and 720.5?

Related question, in case Lethal Vapor counts as an object involved in the loop: Assume there is a Pithing Needle naming Lethal Vapors, and the active player also controls Seal of Cleansing. The only legal game choice remaining would be to activate Seal of Cleansing. Does the player have to do that, and if not, is the game a draw?

  • I don't think that 720.3 applies to the situation you specified. Lethal Vapors is not an optional ability, so the active player cannot choose anything other than resolving it once it's been triggered.
    – J. Sallé
    May 14, 2018 at 16:20
  • Lethal Vapors has an activated ability too, one that would end the loop, so 720.5 does potentially apply.
    – Hackworth
    May 14, 2018 at 16:22
  • Of course. I totally ignored that fact. In that case, I believe Lethal Vapors would indeed be an object involved in the loop, so you could activate its ability without contradicting 720.5. That said, I believe the second example with the Seal of Cleansing would indeed end in a draw unless the AP chose to sacrifice the seal.
    – J. Sallé
    May 14, 2018 at 16:25
  • 1
    Passing priority is never illegal.
    – murgatroid99
    May 14, 2018 at 20:00
  • 1
    @Hackworth "A player can't choose to not take an action unless he concedes." That's not correct. Choosing not to perform an action is the definition of passing. Passing isn't an action, although it is a game choice.
    – Arthur
    May 15, 2018 at 8:47

4 Answers 4


There's no contradiction.

720.5 is an explanation of how to follow 720.3 in some cases. For example, if Lethal Vapors said "destroy it or sacrifice another permanent", then the creature's owner would have to sacrifice something else to end the loop. That's the kind of choice that is called for by 720.5.

In your example, neither player can be forced to activate Lethal Vapors. This is according to 720.5. The activated ability on Lethal Vapors is not called for by any object involved in the loop.

Either player however, would be able to choose to activate Lethal Vapors to end the sequence. Thus you have a situation which is legally allowed to end in a draw if both players agree, but either player could skip their next turn to keep the game going.

The key here is that 720.5 doesn't try to include "abilities of anything involved in the loop" in the scope. It just means when the mechanism of the loop inherently includes a way out - a player can't endlessly choose the other option to force a draw.

  • The case of "destroy it or sacrifice another permanent" is addressed by 720.6.
    – Arthur
    May 15, 2018 at 6:42
  • @Arthur 720.6 applies only in cases where the choice is presented as an "unless". Normally my example would be templated like that, but not necessarily. An example is Tainted Aether combined with Solemnity and a creature with Undying. The rule would force the player, if possible, to eventually sacrifice something other than the undying creature.
    – Samthere
    May 15, 2018 at 8:52

There is no contradiction here because rule 720.3 does not apply to this situation. "Pass priority" is not a game action on the same level as activating an ability or casting a spell. It is inaction and it is the default choice. The loop that you describe does not involve players taking actions, but rather players passively allowing game events to play out. So, no player is required to activate Lethal Vapors' ability, and the game is a draw unless a player chooses to take that action.

This has been confirmed by a ruling from the Level 3 judge who runs the Ask a Magic Judge tumblr blog. I asked this question and got the quoted answer

I would like to get a clarification on the infinite loop rules. Say the battlefield includes a Solemnity and a Lethal Vapors, and a player casts a Young Wolf, which has Undying. That creature will keep dying and returning in a loop because it never gets a counter. Does that cause the game to end in a draw? Is any player required to activate Lethal Vapors' other ability or take some other action to break the loop?

No, they’re not required to do so. The game will end in a draw if no one chooses to destroy the Lethal Vapors.


There's no contradiction.

  • CR 720.3 prevents a loop of voluntary actions.
  • CR 720.5 allows a loop of mandatory actions.

Only one of them applies to a given loop.

The loop you are describing isn't a fragmented loop; it's a loop of mandatory actions. That means that unless someone breaks it, the game ends in a draw.[CR 720.4, 104.4b, 104.4f] But it also means that noone is forced to break it even if they could.[CR 720.5]


An example of a fragmented loop would be if there were 3 Oblivion Rings (owned by 2 or more players) that are each entering the battlefield and exiling each other in a triangle. An example of an action that could break the loop, as prescribed by rule 720.3, would be if there was a legal target for Oblivion Ring besides another Oblivion Ring. In this case, rule 720.3 would force the active player to exile the other legal target, even if it strategically not desired.

Example: In a multiplayer game, Player 1 controls an Oblivion Ring that has exiled Player 2's Oblivion Ring. Player 2 casts an Oblivion Ring, hoping to take down some other strategic target. With Oblivion Ring on the stack, Player 3 responds by bouncing the strategic target with an Unsummon. Now when the Oblivion Ring resolves, it must either target player 3's Abyssal Persecutor or Player 1's Oblivion Ring. Neither Player 1 nor Player 2 want to exile the Abyssal Persecutor, because they are both at 0 life. They want to juggle Oblivion Rings forever, but Rule 720.3 obligates Player 2 to break the loop by exiling something besides an Oblivion Ring. Therefore, Player 2 is forced to exile Abyssal Persecutor, thus killing both Player 1 and Player 2.

An example of an application of Rule 720.5 is that if the active player has a Ray of Revelation in their graveyard, they are not obligated to flash it back in order to break the Oblivion Ring loop, because the Ray of Revelation is not an object that is involved in the loop.

  • Welcome to the site! If you use [mtg:cardname], it will auto-link to Gatherer, which will help give context to your answer.
    – GendoIkari
    May 14, 2018 at 19:32
  • @Gendolkari Unless the card you link has a name which is contained in the name of other cards. Just a heads-up.
    – Arthur
    May 15, 2018 at 6:44
  • And isn't it player 2 who is obligated to remove the persecutor, since it is he who is first faced with the exact same game state for the second time?
    – Arthur
    May 15, 2018 at 6:46

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