
WitherWitherThis deals damage to creatures in the form of -1/-1 counters. (This deals damage to creatures in the form of -1/-1 counters.)
When this creature enters, it deals 1 damage to each creature your opponents control.
Whenever a creature an opponent controls with a counter on it diesdiesA creature dies when it goes from the battlefield to a graveyard. Being exiled or returned to hand is not dying., you create a tapped Treasure tokenTreasure tokenA Treasure is an artifact token with ", Sacrifice this token: Add one mana of any color.".
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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.