Urza, Lord High Artificer + Forensic Gadgeteer + Sensei's Divining Top + Cloud Key

Urza, Lord High Artificer

Forensic Gadgeteer

Sensei's Divining Top

Cloud Key

How it works

1. Cast Sensei's Divining Top by paying 0.
2. Forensic Gadgeteer triggers, creating a Clue token.
3. Activate Urza's first ability by tapping the Clue, adding .
4. Activate Sensei's Divining Top's second ability by tapping it, causing you to draw a card and put Sensei's Divining Top from the battlefield on top of your library.
5. Activate the Clue by paying 1 and sacrificing it, causing you to draw Sensei's Divining Top from the top of your library.
6. Repeat.

This clever loop relies on forensic cost reduction to generate an infinite, mana-positive cycle with Sensei's Divining Top. With Cloud Key naming "artifact," your Sensei's Divining Top costs nothing to cast, while Forensic Gadgeteer provides a Clue token on cast and discounts your artifact activations—allowing that Clue to tap for blue mana thanks to Urza, Lord High Artificer. You then tap Sensei's Divining Top to draw a card and put it on top of your library, and use the Clue's mana to sacrifice itself and draw the Top right back out.