Sensei's Divining Top + Foundry Inspector + Rook Turret

Sensei's Divining Top

Foundry Inspector

Rook Turret

How it works

1. Cast Sensei's Divining Top by paying 0 due to Foundry Inspector.
2. When Sensei's Divining Top enters, Rook Turret triggers.
3. Holding priority, activate Sensei's Divining Top by tapping it, causing you to draw a card and put Sensei's Divining Top on top of your library.
4. Resolve the Rook Turret trigger, causing you to draw Sensei's Divining Top from your library, and then discard a card other than Sensei's Divining Top.
5. Repeat

This elegant loop turns Sensei's Divining Top into a self-sustaining engine by manipulating the stack. Foundry Inspector provides the crucial cost reduction that makes Sensei's Divining Top free to cast, while Rook Turret watches your artifacts arrive and triggers a draw-and-discard exchange. By tapping Sensei's Divining Top to draw a card in response to that enter-the-battlefield trigger, you cleverly place the artifact back on top of your library just in time for Rook Turret's effect to draw it right back out, letting you cycle through your deck endlessly.