Falco Spara, Pactweaver + Sensei's Divining Top + Umori, the Collector + Arcbound Crusher

Falco Spara, Pactweaver

Sensei's Divining Top

Umori, the Collector

Arcbound Crusher

How it works

1. Activate Sensei's Divining Top's second ability by tapping it, causing you to draw a card and put Sensei's Divining Top on top of your library.
2. Cast Sensei's Divining Top from the top of your library by paying 0 and removing a counter from a creature you control.
3. When Sensei's Divining Top enters, Arcbound Crusher triggers, putting a +1/+1 counter on Arcbound Crusher.
4. Repeat.

This loop turns Sensei's Divining Top into a self-sustaining engine by tapping it to draw a card and place itself back on top of your library. From there, Falco Spara, Pactweaver lets you recast Sensei's Divining Top directly from the top of your library for free by using its alternate cost, paying for it simply by stripping a counter off a creature you control. Meanwhile, Umori, the Collector quietly ensures your spells are cheaper, and every time Sensei's Divining Top re-enters the battlefield, Arcbound Crusher triggers to continuously pile up new +1/+1 counters to fuel Falco Spara, Pactweaver's alternate casting cost indefinitely.