Twilight Drover + Phyrexian Altar + Adrix and Nev, Twincasters

Twilight Drover

Phyrexian Altar

Adrix and Nev, Twincasters

How it works

1. Activate Twilight Drover by paying 2 and removing a +1/+1 counter from it, creating four 1/1 Spirit creature tokens with flying.
2. Activate Phyrexian Altar three times by sacrificing three Spirits, adding 2.
3. When the Spirits die, Twilight Drover triggers three times, putting three +1/+1 counters on itself.
4. Repeat.

This clever loop lets you turn a single +1/+1 counter on Twilight Drover into an exploding engine of spirits and mana, perfectly fueled by the sacrifice outlet Phyrexian Altar. The secret multiplier is Adrix and Nev, Twincasters, whose replacement effect doubles the tokens created by Twilight Drover's activation from two into four. Sacrificing three of those newly minted spirits to Phyrexian Altar effortlessly refunds the exact mana needed to activate Twilight Drover again, while the fourth spirit (alongside the ones just sacrificed) leaves the battlefield to continuously replenish the +1/+1 counters required to keep the loop going.