Falco Spara, Pactweaver + Sensei's Divining Top + The Thirteenth Doctor + Cloud Key

Falco Spara, Pactweaver

Sensei's Divining Top

The Thirteenth Doctor

Cloud Key

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 by paying 0 and removing a counter from a creature you control.
3. The Thirteenth Doctor triggers, putting a +1/+1 counter on it.
4. Repeat.

This crafty loop turns your library into an endless well of card draw by leveraging Falco Spara, Pactweaver to cast artifacts from the top of your deck for zero mana. You can pull this off because Cloud Key discounts artifacts down to costing nothing, letting Sensei's Divining Top be continuously recast directly from the library without ever needing actual mana. Meanwhile, The Thirteenth Doctor feeds the engine by steadily placing +1/+1 counters on your creatures each time a spell is cast from outside your hand, ensuring Falco Spara always has fresh counters to fuel the next iteration.