This elegant two-card loop relies on the sheer mana-producing power of Llanowar Tribe, which taps to generate three green mana on demand—just enough to pay the activation cost of Umbral Mantle. By using that exact mana to activate the Mantle's untap ability, you ready the Tribe to tap for mana all over again while growing its power and toughness with each iteration. Because the equipment's equip cost is a mere zero mana, it attaches seamlessly to begin the cycle, leaving you with an infinitely large creature ready to crash through for a game-winning blow.