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• Mirror Room // Fractured Realm

  2U5UU

  Enchantment — Room // Enchantment — RoomU

  Mirror Room makes Rumbling Crescendo's triggered ability trigger an additional time — each time it fires, you get it twice. Value, not a loop.
• Rings of Brighthearth

  3

  ArtifactC

  Rumbling Crescendo has activated abilities that aren't mana abilities, fueling Rings of Brighthearth's activation-trigger.