I'm confused about how to interpret the rules regarding infinity. In particular, the rules speak of mandatory actions, from which I infer that there are also non-mandatory actions. How do I tell which are which? Are there such things as non-actions? If so, how do I tell them apart from actions?
I would like to understand the terms, concepts and ways of applying the rules. For that purpose, here are some concrete scenarios:
Scenario 1: Each player controls Platinum Angel enchanted with a Pacifism and has the remaining 58 cards exiled (no hand, no library, nothing else in play or graveyard). My intuition suggests this is a draw.
I think the complete game state graph is a simple cycle whose length is the number turns per round (here equal to the number of players, two) times the number of times players pass priority in a do-nothing turn (the number of players times the number of steps in which players have priority, which is always the same).
Since no player can do anything other than pass priority, the way I can get to a draw by reading the rules is if this is a sequence of only mandatory actions. An open question: is this an empty sequence of actions, meaning passing priority is a non-action, or is it a sequence of some positive number of mandatory actions, all of them being passing priority?
Scenario 2: Like scenario 1, but player 1 also has Mox Diamond in hand. Player 2 knows this, thanks to e.g. a Gitaxian Probe.
I think the state graph is two parallel cycles, with an edge from one to the other---but not in the other direction---whenever player 1 could cast Mox Diamond, which would go to his graveyard since he doesn't have a land to discard. The game is initially somewhere in that loop which can reach the other.
No state in the state graph is won or lost for either player, so I think the game should be a draw. The only way to get there, AFAICT, is if the current "loop" is one of only mandatory actions. But passing when you could play Mox Diamond could not be mandatory in the sense of you not being allowed to play Mox Diamond---could it?! But neither could playing Mox Diamond be mandatory, since you're allowed to not play the cards you have in hand. Hence I believe that passing priority is a non-action, and scenario 1 consists of an empty sequence of mandatory actions.
Scenario 3: Like scenario 1, but replace both copies of Pacifism with Cloak of Mists and give each player an Energy Field.
The same empty loop of mandatory actions from scenario 1 still exists. A player could also choose to attack (not mandatory). This would tap their Platinum Angel, but not change any life total, thanks to Energy Field. The non-trivial part of the state space is the tapped/untapped state of each Platinum Angel, with a lot of passing of priority to flip back and forth between those four state( group)s.
Does rule 716.3 take effect here?
716.3. 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. Example: In a two-player game, the active player controls a creature with the ability "{0}: [This creature] gains flying," the nonactive player controls a permanent with the ability "{0}: Target creature loses flying," and nothing in the game cares how many times an ability has been activated. Say the active player activates his creature's ability, it resolves, then the nonactive player activates her permanent's ability targeting that creature, and it resolves. This returns the game to a game state it was at before. The active player must make a different game choice (in other words, anything other than activating that creature's ability again). The creature doesn't have flying. Note that the nonactive player could have prevented the fragmented loop simply by not activating her permanent's ability, in which case the creature would have had flying. The nonactive player always has the final choice and is therefore able to determine whether the creature has flying.
If so, what are its implications? Here is one interpretation of the rule: if a player could make a choice that would bring the game into a state in which it has been before, that player may not make that choice. But since the state space is finite in this scenario, sooner or later there will be a game state in which a player is not allowed to do anything: they are neither allowed to pass priority, nor not pass priority, all (other?) actions having been forbidden by my interpretation of this rule. The game can not continue from such a state, but neither is the outcome well-defined. Hence I think my interpretation is wrong. But I don't know how else to interpret it.
Does it only apply to loops that do not cross turn boundaries? If so, how is this situation resolved? Does the loop of mandatory actions rule apply, making the game a draw?
Does Energy Field matter? Does Cloak of Mists? There are ten combinations: three quantities of each permanent, 0 or 1 or 2, and in case of 1 and 1, whether they are controlled by the same player or not. (Maybe times two, depending on whose turn it is when we enter this scenario for the first time.)
Scenario 4: players control only Platinum Angel. Both players have one million life.
Same questions as scenario 3. Is a player ever forced to block (and lose)? Assume it is the untap step of player 1's turn and both angels are untapped. Do the life totals matter? Does it change if they're 1? If they're -1? If one is positive and one negative?
Scenario 5: like scenario 4, but player 1 also controls a Swamp and has a Mox Diamond in hand, known via Gitaxian Probe.
Same questions as the previous scenario.
Scenario 6: like scenario 5, but player 1 has a Vendetta in hand instead of Mox Diamond.
Same questions as the previous scenario. In particular: is it a drawn game immediately, even though player 1 could force a win if play continued? That would seem bizarre.
Do the answers in scenario 5 and 6 depend on the card in hand being known? If so, how?
Exactly at what scenario does it stop being a draw and become won for either player?
Scenario 7 ("Here be dragons"): both players have Worldgorger Dragon in their graveyard. Player 1 has an Animate Dead on the stack, targeting his own Worldgorger Dragon. All 117 other cards are exiled.
Whenever Animate Dead re-enters play, player 1 must choose a target for it. He will only have two valid targets ever. Is targeting his own dragon a mandatory action? Is targeting the other player's dragon a mandatory action? Are two mutually exclusive actions mandatory, and what does that mean? Is neither action mandatory, making the drawn-game-on-mandatory-loop rule not apply? If it is only the choosing of a target that is mandatory, but not a particular target, would the game also be drawn with a Birds of Paradise in some graveyard (since the loop of always choosing dragon still exists)?