Dualcaster Mage + Echo Storm + Encroaching Mycosynth

Dualcaster Mage

Echo Storm

Encroaching Mycosynth

How it works

1. Cast Echo Storm by paying 3, targeting Dualcaster Mage.
2. Echo Storm triggers, creating a copy of itself, targeting Dualcaster Mage.
3. Resolve the copy of Echo Storm, creating a token copy of Dualcaster Mage.
4. When the Dualcaster Mage token enters the battlefield, it triggers, creating a copy of Echo Storm, targeting Dualcaster Mage.
5. Repeat from step 3.

By turning every nonland permanent and spell you control into an artifact thanks to Encroaching Mycosynth, Echo Storm suddenly gains a remarkably wide array of potential targets, including creatures already on your battlefield. When you cast Echo Storm targeting Dualcaster Mage, the spell's resolution produces a token copy of the Mage right onto the battlefield. That token's entry triggers its ability to copy the original Echo Storm, feeding the loop anew to continually generate infinite Magecraft triggers, infinite creature entry triggers, and an endlessly growing army of Dualcaster Mage tokens.