Whenever enchanted player is attacked, create a colorless artifact token named Gold. It has "Sacrifice this artifact: Add one mana of any color." Each opponent attacking that player does the same.
8/25/2017 Curse of Opulence’s triggered ability resolves after attackers have been declared. Any costs to attack must have already been paid before the attacking player creates the Gold.
8/25/2017 Each Curse’s ability triggers only once, no matter how many creatures are attacking the enchanted player.
8/25/2017 A player is attacking another player if they control a creature that’s attacking that player. If no creatures are attacking the enchanted player as a Curse’s ability resolves (most likely because they’ve left the battlefield), only the Curse’s controller performs its actions.
8/25/2017 The triggered ability of these Curses won’t trigger if only a planeswalker controlled by the enchanted player is attacked.
8/25/2017 If you enchant yourself with one of these Curses, you’ll get its effects whenever another player attacks you.