豊穣の角笛
When you play this, gain a card costing up to 1 Coin per differently named card you have in play (counting this). If it's a Victory card, trash this.
Horn of Plenty is a Treasure from Cornucopia. Instead of producing +Coin as other Treasure cards do, however, Horn of Plenty is a gainer. It allows you to gain a card with a cost of up to 1 Coin for each different card you have in play, thus rewarding you for playing a variety of cards.