How do "loops" and drawing work?
Asked by Epidilius 9 years ago
According to the comp rules, if the game enters a loop of ONLY mandatory actions, the game is a draw.
So, Duskmantle Guildmage + Mindcrank means the game is a draw (if you trigger his ability). What happens if you have a Bloodchief Ascension on the field too?
Does this form two "loops" (ascension and mindcrank, and guildmage and mindcrank)? Or is it now one loop with an optional action?
"716.4. If a loop contains only mandatory actions, the game is a draw. (See rules 104.4b and 104.4f.)"
Duskmantle Guildmage + Mindcrank forms a loop of only mandatory actions, though. How does it not end in a draw?
And as for Bloodchief Ascension , I was more curious as to what happens if the guildmage's ability has been activated. Is it one loop, or two?
September 19, 2014 7:45 p.m.
Epochalyptik says... #3
@Epidilius: Because your opponent will run out of life and lose the game.
With Bloodchief Ascension , you have one mandatory loop and one optional loop, but your opponent will still lose when he or she runs out of life.
September 19, 2014 7:49 p.m.
@Epochalyptik:
That, or the opponent will run out of cards from his or her library, if he or she has enough life to survive the milling.
September 19, 2014 8:07 p.m.
GlistenerAgent says... #5
Note that if the opponent is at a very high life total (high enough that he would have no cards in his library before he died), this loop does end in a draw. Mindcrank does not require the opponent to draw any cards, and then can only lose when they have to draw from an empty library. When their library is milled out, the loop ends because Mindcrank can't take effect anymore.
In general, infinite loops that result in one player or the other losing the game will end because the game itself ended.
September 19, 2014 8:25 p.m.
Epochalyptik says... #6
@GlistenerAgent: You contradicted yourself. If the opponent runs out of cards in his or her library, the the loop just ends (after all of the abilities on the stack and any abilities that trigger as a result resolve). The game will continue.
September 19, 2014 8:28 p.m.
The relevant factor in this question is that both abilities are triggered abilities which means they go onto the stack, resolve, and the resolution of one triggers the other back and forth.
But since they are triggered abilities, there must be a pass of priority before one will resolve, which is a point in which state based actions are checked. Since the player would lose the game for having 0 or less life as a state-based action, in a 2-player game, them losing causes you to win and the game to end.
September 19, 2014 10:52 p.m.
Like...people see a loop like that and imagine it spiralling out of control, but there's only ever one triggered ability on the stack, and both players have a chance to respond before it resolves.
You could set up that combo, and with Mindcrank 's trigger on the stack, cast Shatter . There's, in game terms, plenty of time between each ability's resolution in which you can respond, or lose the game.
September 19, 2014 10:57 p.m.
Colten_Lee says... #9
If you don't mind, could somebody elaborate on how the 3 Oblivion Ring is an infinite loop...
September 20, 2014 3:52 a.m.
Epochalyptik says... #10
It's a loop if there are no other nonland permanents on the battlefield. Say you have an Oblivion Ring exiling another Oblivion Ring . A third Oblivion Ring then enters the battlefield, and the only legal target is the first Oblivion Ring . Exiling that Oblivion Ring causes its LTB ability to trigger and return the originally-exiled Oblivion Ring , which can now only target the third Oblivion Ring . The cycle continues and causes the game to end in a draw.
September 20, 2014 4:36 a.m.
Epochalyptik says... #11
Also, it's worth noting that if a loop of mandatory actions is established, no player needs to take an extra action to break the loop, even if they could take such an action. For example, no player is forced to Naturalize an Oblivion Ring in the loop described above, even if that player could Naturalize one and end the mandatory loop.
This is not the same as players being forced to end nonmandatory loops. If a loop of actions is not mandatory, it must end at some point. Say there were a fourth nonland permanent in the Oblivion Ring loop. Eventually, you'd be forced to target the other nonland permanent and break the loop. The difference between this scenario and the one described in the previous paragraph is that there exists within the loop an option that would cause the loop to end. The game considers these options (e.g. other targets, other choices, "may" effects) while processing the loop, but it does not consider "extra" options like players casting spells or activating abilities.
September 20, 2014 4:40 a.m.
Colten_Lee says... #12
Ahh, it makes sense that it only works with no other ninland permanents out. I read it and I thought that it wasn't bc of the while permanents not having memory of its previous existence... So you could just target a different permanent. But not I'd their are none. Thanks.
And okay that makes sense, like say you're listing and you can't figure out a way to prevent that. Someone intentionally/unintentionally creates a loop that you can stop, you can avoid the loss and just let it happen.
September 20, 2014 7:04 a.m.
At what point, then, is a series of repetitive action considered a loop? I ask because the rule I quoted above (716.4) seems pretty straightforward. If there's a loop with only mandatory actions, the game is over.
It doesn't say anything about how long it has to go on for, if it will eventually end or not, or if you can respond to the loop.
September 20, 2014 9:05 p.m.
Epochalyptik says... #14
It's a loop the second it starts going back and forth, but it only results in a draw if the game wouldn't end anyway as a result. The game doesn't instantaneously end the moment it detects a loop. You're reading the rule a bit too absolutely.
September 20, 2014 9:12 p.m.
Aren't the comp rules supposed to be read literally?
September 20, 2014 9:16 p.m.
They are. But you're missing the point. After each cycle of that loop, the game state has actually changed (They opponent has one more card in the graveyard and one less life) which means that while the game is in a loop, the state is measurably changing, so you continue to process the loop.
It's only when the loop -would- continue forever that the game ends in a draw.
September 20, 2014 9:35 p.m.
Epochalyptik says... #17
Yes, but you're being too absolute. I don't know how else to explain this to you. Maybe Rhadamanthus or someone could do it better. The game ends in a draw only if the loop would not end the game. It may be that a loop that ends the game is not considered a loop of mandatory actions because it must end at the point at which it would end the game.
September 20, 2014 9:38 p.m.
Pay attention to
104.4b If a game that's not using the limited range of influence option (including a two-player game) somehow enters a "loop" of mandatory actions, repeating a sequence of events with no way to stop, the game is a draw. Loops that contain an optional action don't result in a draw.
to the phrase "with no way to stop"
You can clearly observe in the mandatory loop of Mindcrank and Duskmantle Guildmage that it absolutely has a way to stop, which is that the player will eventually run out of life or their library which will stop the loop.
September 20, 2014 9:41 p.m.
CrazyLittleGuy says... #19
I think I can explain a little more. The Duskmantle Guildmage and Mindcrank loop creates a series of repeating triggered abilities. Each times an ability is triggered, it goes on the stack, and each player gets a round of priority to respond to it. Once that ability resolves, the other permanent will trigger, the ability will go on the stack, both players will get priority, then it resolves, then the next one triggers, etc.
Now, the important thing is that whenever a player would get priority, state-based effects/actions are checked/taken. This means that if a player is at 0 or less life, they lose the game as a result of the state check. So, any abilities or spells on the stack are no longer relevant, as a player has now lost the game and it ends immediately.
September 20, 2014 10:46 p.m.
Epochalyptik says... #20
@CrazyLittleGuy: I think he's more concerned with the interpretation that the loop, once begun, must immediately end the game.
September 20, 2014 11 p.m.
CrazyLittleGuy says... #21
Oh, well in that case, a good rule of thumb is that once a mandatory loop of actions starts, assume it takes place an arbitrarily large number of times, then analyze the board state and let that tell you how the game ends. In this case, you're assuming both triggers happen ~infinite times, at which point your opponent will be quite dead. However, if upon checking the board after a massive number of mandatory repetitions tells you that both players are still alive, the game will end in a draw.
September 21, 2014 12:22 a.m.
Rhadamanthus says... #22
The key concept is the "with no way to stop" that Devonin pointed out earlier. If you're trying to do a close reading of the CR, pay attention to which terms it specifically defines, and only use those specific definitions when interpreting the ruels.
In the original example, the opponent will eventually (the number of steps is easy to calculate) either reach 0 life or an empty library. If 0 life happens first then the player leaves the game, there's no more library for Mindcrank to act on, it will stop triggering Dimir Guildmage , and the loop stops. If empty library happens first then there's no more library for Mindcrank to act on, it will stop triggering Dimir Guildmage , and the loop stops.
Yes, before anyone decides to get clever, there are ways to construct a situation where this loop doesn't end (Progenitus + Angel's Grace , etc.).
September 21, 2014 10:50 p.m.
Thanks for all the answers. I really appreciate the time you took to help me out.
I understand how loops and drawing work now. I guess I either misread or was too austere in my interpretation of the rules. Thanks again.
Epochalyptik says... Accepted answer #1
Duskmantle Guildmage + Mindcrank doesn't usually produce a draw. If your opponent loses, then the loop will end and you will win.
Because Bloodchief Ascension 's ability is a "may" ability, it can't form an infinite loop. If the game won't end from you killing a player, you must eventually choose to stop repeating the loop.
To expand, though, a loop of mandatory actions ends in a draw if it doesn't cause all but one player or team to lose the game. Something like three Oblivion Ring s exiling each other is an example.
September 19, 2014 7:21 p.m.