Sensei's Divining Top + Transplant Theorist + Cloud Key

Sensei's Divining Top

Transplant Theorist

Cloud Key

How it works

1. Cast Sensei's Divining Top by paying 0 due to Cloud Key.
2. When Sensei's Divining Top enters, Transplant Theorist 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 Transplant Theorist 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 clever engine turns Sensei's Divining Top into a self-sustaining loop by using Cloud Key to reduce its casting cost to zero. Whenever Sensei's Divining Top enters the battlefield, Transplant Theorist triggers to let you draw and discard, but responding by activating the Top's own ability puts it safely on top of your library instead. When the loot trigger resolves, you draw Sensei's Divining Top right back out of your library, ready to be recast for free and churn through your entire deck.