Sensei's Divining Top + Mystic Forge + Gran-Gran

Sensei's Divining Top

Mystic Forge

Gran-Gran

How it works

1. 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.
2. Cast Sensei's Divining Top from the top of your library by paying 0.
3. Repeat

This elegant loop relies on Mystic Forge granting you permission to cast artifact spells directly from the top of your library, allowing Sensei's Divining Top to be played for free once you've set up its cost reduction. By tapping Sensei's Divining Top to draw a card and place itself back on top of your library, you set up the very next card for Mystic Forge to cast again. Meanwhile, Gran-Gran sits on the battlefield filtering your hand with every tap and potentially shaving mana off your noncreature spells if your graveyard is well-stocked with Lessons, turning this self-referential top-spinning into endless card draw and a towering storm count.