Nadu, Winged Wisdom, Scute Swarm, and Umbral Mantle

Prerequisites

• Nadu, Winged Wisdom on the battlefield
• Scute Swarm on the battlefield
• Umbral Mantle on the battlefield

Steps

1. Activate Umbral Mantle's equip ability by paying , targeting a creature you control
2. The creature triggers, causing you to reveal the top card of your library and put it onto the battlefield if it's a land card, or put it into your hand otherwise
3. If a land was put onto the battlefield, each Scute Swarm you control triggers, creating either that many 1/1 Insect creature tokens or that many token copies of Scute Swarm
4. Resolve the equip ability from step 1
5. Repeat as able

Results

• Near-infinite ETB
• Near-infinite creature tokens
• Near-infinite card draw
• Near-infinite landfall