Kentaro, the Smiling Cat + Whitemane Lion + Urza's Incubator + Rukarumel, Biologist

Kentaro, the Smiling Cat

Whitemane Lion

Urza's Incubator

Rukarumel, Biologist

How it works

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

This clever loop transforms free-casting into an endless storm and trigger engine by harmonizing cost reduction with self-bouncing mechanics. Rukarumel, Biologist sets the foundational type by making all your creatures and creature spells Slivers, allowing Urza's Incubator to shave {2} off their costs. With Kentaro, the Smiling Cat in play, those Samurai spells (which are now also Slivers thanks to Rukarumel) can be cast for free when their mana value matches the reduction, enabling you to cast Whitemane Lion for zero mana. As Whitemane Lion enters the battlefield, its own triggered ability forces you to return a creature you control to your hand—naturally targeting itself—so you can endlessly repeat the process for infinite entry and leave-the-battlefield triggers.