Infinite Loops and Bounce
Asked by Epidilius 8 years ago
I know that an infinite loop ends the game in a draw. I know that the rules define an infinite loop as a series of mandatory actions. I read that as a series of cards that don't have the word "may" in their text.
The most classic game ending loop is the triple Oblivion Ring loop. If nothing but three O Rings are on the field, A will exile B, returning C, which exiles A, returning B, which exiles C, returning A, etc. Because O Ring doesn't have "may" in its text, you have to exile another card, and this causes an infinite loop.
A more relevant loop is if I have a Sporemound and a Life and Limb. A land enters the field, which creates a 1/1 Saproling, which is also a land, which creates a 1/1 Saproling, etc. This cannot end, and according to the rules the game now ends in a draw.
My question is what if you have a Boomerang in your hand? Does the game end anyway? Do you have to declare it right away, even if you don't cast it right away? Can I choose to let the combo trigger a certain amount of times before the game ends, or does it end right away?
I guess my questions can be boiled down to:
"When does an infinite loop end the game? The instant it begins? One iteration? Ten iterations? Infinite iterations?"
"Does having a Boomerang in hand and the mana to cast it mean a loop is no longer infinite?"
This has been bugging me for ages, and I'd appreciate some help.
Rhadamanthus says... #2
The only time someone is required to interrupt a loop is if they're able to make a different choice for some action in the loop that would end it. Like Raging_Squiggle says, it ends up coming down to the rules about shortcuts. If you want to interrupt a mandatory loop with your Boomerang after a certain number of iterations, just say so. If you'd rather let the game end, simply do nothing.
December 23, 2015 2 p.m.
merrowMania says... #3
Reiterateing what the above two said: a player is only required to disrupt an infinite loop if the means to do so is in a public zone (grave, exile, battlefield), even if both players know that the means is in a player's hand (such as from a Thoughtseize earlier in the game) or some other hidden zone. Just a fun fact if you want to make a game a draw.
I'll look around for an actual ruling to back this up.
December 23, 2015 5:54 p.m. Edited.
merrowMania says... #4
Okay, nevermind. You are NEVER forced to stop an infinite loop:
716.5. 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.
Example: A player controls Seal of Cleansing, an enchantment that reads, Sacrifice Seal of Cleansing: Destroy target artifact or enchantment. A mandatory loop that involves an artifact begins. The player is not forced to sacrifice Seal of Cleansing to destroy the artifact and end the loop.
This is because it would force a player to make a decision that could harm their position in the game, thereby giving the opponent an unfair advantage for simply happening to be the one to not have to resources to break the loop.
December 23, 2015 6:06 p.m. Edited.
Epidilius,
Just a quick point of clarification: You can totally play Life and Limb
+
Sporemound
without a draw.
You're referring 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.
The key part of the ruling is "...with no way to stop..." Just drop the Sporemound in a sac' engine or put some instant-speed Enchantment removal on the stack to kill the Life and Limb, and you're good for an arbitrarily large number of Saprolings, not an infinite amount.
Here's a short Wizards article on the subject that I found helpful.
January 7, 2016 4:33 p.m.
Raging_Squiggle says... #6
As was stated above. If someone has a way to end the mandatory infinite loop, a shortcut can be proposed, repeating the loop 
amount of times before stopping it either via sacrifice Ashnod's Altar, destruction Doom Blade, bouncing Boomerang, countering Stifle, or otherwise ceasing the loop in another way.
January 7, 2016 5:16 p.m.
Raging_Squiggle,
Yeah, I totally agree with you (and Rhadamanthus and merrowMania). I had just stumbled on this and wanted to pile on with a piece about 104.4b ... 716 is great for explaining how to get out of a loop, but I like 104.4b too, for explaining why
Raging_Squiggle says... Accepted answer #1
You have two options. Normally it would end in a draw. But since you have an available response to stop it, it doesn't necessarily have to end in a draw.
Scenario 1. You let the loop go infinitely and the game ends in a draw.
716.4. If a loop contains only mandatory actions, the game is a draw. (See rules 104.4b and 104.4f.)
Scenario 2. You propose a shortcut, allowing the loop to repeat X amount of times before you stop it with your Boomerang.
December 23, 2015 1:30 p.m.