Barrin, Master Wizard + Myr Battlesphere + Ashnod's Altar + Panharmonicon

Barrin, Master Wizard

Myr Battlesphere

Ashnod's Altar

Panharmonicon

How it works

1. Cast Myr Battlesphere by paying 7.
2. When Myr Battlesphere enters the battlefield, it triggers twice, creating eight 1/1 Myr artifact creature tokens.
3. Activate Ashnod's Altar five times by sacrificing five Myrs, adding ten C.
4. Activate Barrin by paying 2 and sacrificing a Myr, returning Myr Battlesphere to your hand from the battlefield.
5. Repeat.

This clever loop revolves around doubling up on entry triggers using Panharmonicon so that casting Myr Battlesphere floods your board with eight Myr artifact creature tokens instead of just four. You then feed five of those newly minted tokens into Ashnod's Altar to generate the colorless mana needed to fuel Barrin, Master Wizard, whose activated ability bounces the original Myr Battlesphere right back to your hand. Because you spend only five mana to pull off the loop while netting ten mana from the Altar sacrifices, you generate infinite colorless mana along with an endless stream of entering, leaving, and dying creatures.