When Nether Traitor dies, Golgari Germination triggers, creating a 1/1 Saproling creature token.
Activate Phyrexian Altar by sacrificing the Saproling, adding one mana of any color.
When the Saproling dies, Nether Traitor triggers, causing you to pay ({B} magic symbol) to return Nether Traitor from your graveyard to the battlefield.