({1} magic symbol) , plus either ({B} magic symbol) , ({R} magic symbol) or ({G} magic symbol) available available.
Steps
Activate Phyrexian Altar twice by sacrificing Beetleback Chief and Slimefoot and Squee, adding two mana in any combination of ({B} magic symbol) , ({R} magic symbol) or ({G} magic symbol) .
Activate Slimefoot and Squee by paying ({1} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) and sacrificing a Saproling, returning it and Beetleback Chief from your graveyard to the battlefield.
When Beetleback Chief and Slimefoot and Squee enter the battlefield, their abilities trigger.
Resolve the Slimefoot and Squee trigger, creating a 1/1 Saproling creature token.
Resolve the Beetleback Chief trigger, creating two 1/1 Goblin creature tokens.
Activate Phyrexian Altar four times by sacrificing the two Goblins, Beetleback Chief and Slimefoot and Squee, adding ({1} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) .