Cumulative upkeep

Cumulative upkeep is a keyword ability on permanents that requires the permanent's controller to pay an increasing cost each turn, or else sacrifice that permanent. The cost is based on the number of age counters on the permanent. 
==History==
Cumulative upkeep was introduced in Ice Age, reused in Alliances and returned in Mirage block. It returned briefly in Coldsnap, to maintain that set's continuity with Ice Age. The mechanic was also considered for one of the Doctor Who Commander decks.
Through Ice Age and Alliances, Cumulative upkeep was mostly used on enchantments that cause a locking effect on the game, which were flavorfully difficult to maintain and often left little trace after the enchantment was sacrificed. One of the most complex commons in the game, <c>Balduvian Shaman</c>, had Cumulative upkeep as part of its text. In Weatherlight, design experimented with non-mana and nonlife costs, as well as age counter-based effects. Coldsnap introduced functional hybrid mana costs, as well as a cost that had no cap (flipping a coin, on <c>Karplusan Minotaur</c>), with its "cost" being its other associated abilities.
==Rules==
==Rulings==
*Paying cumulative upkeep is always optional. If it's not paid, the permanent with cumulative upkeep is sacrificed. Partial payments of the total cumulative upkeep cost can't be made. For example, if a permanent with "cumulative upkeep " has three age counters on it when its cumulative upkeep ability triggers, it gets another age counter and then its controller chooses to either pay or sacrifice the permanent.
*Examples of choices associated with cumulative upkeep costs include choosing an opponent, choosing a creature, choosing a color of mana, choosing a graveyard, and choosing "heads" or "tails" when flipping a coin. Each choice within a single payment is made independently. The entire set of choices must be legal and payable.
*Some permanents have abilities that trigger when their cumulative upkeep is paid. These abilities trigger when an entire upkeep payment is made. They don't trigger once per individual cost payment.
*Several cards with cumulative upkeep do something based on the number of age counters on them when they're put into a graveyard from play. For example, <c>Arctic Nishoba</c> says "When <c>Arctic Nishoba</c> is put into a graveyard from play, you gain 2 life for each age counter on it." That ability triggers no matter how the Nishoba is put into a graveyard from play. If you don't pay its cumulative upkeep and have to sacrifice it, it gets an age counter first, which impacts the amount of life you gain.
*Note that the decision to track cumulative upkeep using counters was made when the "Sixth Edition rules" (and the original version of the Oracle card database) were released in 1999. The Coldsnap set is the first since that time to feature cumulative upkeep cards, so this may appear to some players to be a rules change.
==Examples==
==Enchantments that impose Cumulative upkeep==
*<c>Mana Chains</c> (Cost: )
*<c>Decomposition</c> (Cost: 1 life)
*<c>Breath of Dreams</c> (Cost: )
*<c>Dreams of the Dead</c> (Cost: )
==References==