Phyrexian Altar and Ashnod's Altar on the battlefield.
({3} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) plus enough mana to pay for commander tax, if applicable available.
Steps
Cast Prossh from the command zone by paying ({3} magic symbol) ({B} magic symbol) ({R} magic symbol) ({G} magic symbol) plus commander tax, if applicable.
Prossh triggers, creating a 0/1 Kobold of Kher Keep token for each mana spent to cast Prossh.