Achtung, man kann nicht "unendlich Leben" sagen, weil unendlich keine Zahl ist. Du kannst aber durchaus einen Term nehmen wie zB 10 hoch 5000, was wohl einen ähnlichen Effekt hat.
Und eine Regel gibts da natürlich auch
421. Handling “Infinite” Loops
421.1. Occasionally the game can get into a state in which a set of actions could be repeated forever. The “infinity rule” governs how to break such loops.
421.2. If the loop contains one or more optional actions and one player controls them all, that player chooses a number. The loop is treated as repeating that many times or until the other player intervenes, whichever comes first.
421.3. If the loop contains at least one optional action controlled by each player and actions by both players are required to continue the loop, the active player chooses a number. The nonactive player then has two choices. He or she can choose a lower number, in which case the loop continues that number of times plus whatever fraction is necessary for the active player to “have the last word.” Or he or she can agree to the number the active player chose, in which case the loop continues that number of times plus whatever fraction is necessary for the nonactive player to “have the last word.” (Note that either fraction may be zero.)
Example: One player controls a creature with the ability “: [This creature] gains flying.” Another player controls a permanent with the ability “: Target creature loses flying.” The “infinity rule” ensures that regardless of which player initiated the gain/lose flying ability, the nonactive player will always have the final choice and therefore be able to determine whether the creature has flying. (Note that this assumes that the first player attempted to give the creature flying at least once.)
421.4. If the loop contains only mandatory actions, the game ends in a draw. (See rule 102.6.)
421.5. If the loop contains at least one optional action controlled by each player and these actions don’t depend on one another, the active player chooses a number. The nonactive player can either agree to that number or choose a higher number. Note that this rule applies even if the actions could exist in separate loops rather than in a single loop.