Kentaro, the Smiling Cat + Cavern Harpy + Urza's Incubator + Maskwood Nexus

Kentaro, the Smiling Cat

Cavern Harpy

Urza's Incubator

Maskwood Nexus

How it works

1. Cast Cavern Harpy by paying 0.
2. When Cavern Harpy enters the battlefield, it triggers, returning itself from the battlefield to your hand.
3. Repeat.

This fascinating loop relies on Maskwood Nexus to blanket your entire board and hand with every creature type, turning every card into a Samurai and allowing Urza's Incubator (naming Samurai) to slash {2} off their mana costs. With that cost reduction in place, Kentaro, the Smiling Cat lets you cast Samurai spells with a mana value of 2 or less—such as Cavern Harpy—for free by paying an X of zero. When Cavern Harpy enters the battlefield, its own triggered ability forces it right back to your hand, enabling you to recast it infinitely for zero mana to farm endless creature enters-the-battlefield triggers, leaves-the-battlefield triggers, and storm count.