Activate Phyrexian Altar by sacrificing Nether Traitor, adding one mana of any color.
Activate Phyrexian Altar by sacrificing another creature, adding .
When the creature dies, Nether Traitor triggers, causing you to pay to return it from your graveyard to the battlefield.
Garrison Excavator triggers, creating a creature token.
Repeat.
This loop transforms your graveyard into an endless engine of life and momentum, powered entirely by the conversion rates of Phyrexian Altar. By sacrificing a creature to generate mana, you set off Garrison Excavator to continually replenish your board with fresh Spirit tokens whenever a card departs your graveyard. Meanwhile, Nether Traitor effortlessly slips back onto the battlefield for a single black mana each time another creature hits the dirt, feeding right back into the Altar to keep the cycle spinning.