Leonardo, Sewer Samurai + Solemnity + Blasting Station + Shield Sphere

Leonardo, Sewer Samurai

Solemnity

Blasting Station

Shield Sphere

How it works

1. Activate Blasting Station by tapping it and sacrificing Shield Sphere.
2. Cast Shield Sphere from your graveyard by paying 0. It will not enter with a finality counter on it due to Solemnity.
3. When Shield Sphere enters, Blasting Station triggers, untapping Blasting Station.
4. Repeat.

This clever recursion engine centers around Leonardo, Sewer Samurai, whose static ability lets you freely recast tiny creatures like Shield Sphere—which boasts a mana cost of zero and a power or toughness of 1 or less—straight out of your graveyard. Ordinarily, casting it this way would slap a finality counter on Shield Sphere to exile it upon death, but Solemnity steps in as a brilliant shield, completely preventing any counters from being placed on creatures. With the path cleared, you can loop Shield Sphere into Blasting Station, sacrificing it to ping any target for damage. Because Blasting Station automatically untaps whenever a creature enters the battlefield, sacrificing and recasting Shield Sphere creates an endless loop of sacrifices and damage that closes out the game on the spot.