
Cumulative upkeepCumulative upkeepAt the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When a player doesn't pay this enchantment's cumulative upkeepcumulative upkeepAt the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it., this enchantment deals X damage to target player or planeswalker and each creature that player or that planeswalker's controller controls, where X is twice the number of age counters on this enchantment minus 2.
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Read from the rules text. A card that enables a keyword makes or is the thing; a card that rewards it gets better when you have it. Two cards interact when one enables what the other rewards.