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Heart of Bogardan

Cumulative upkeep o2
If Heart of Bogardan's cumulative upkeep cost is not paid, Heart of Bogardan deals damage equal to its last paid cumulative upkeep to target player and each creature he or she controls.

Cumulative upkeep {2} (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 Heart of Bogardan's cumulative upkeep, Heart of Bogardan 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 Heart of Bogardan minus 2.