Mana Echoes and Phyrexian Altar on the battlefield.
({1} magic symbol) ({R} magic symbol) ({W} magic symbol) ({B} magic symbol) plus enough mana to pay for commander tax, if applicable, or an additional ({R} magic symbol) , ({W} magic symbol) or ({B} magic symbol) if you haven't cast Jirina from the command zone this game available.
Steps
Cast Jirina from the command zone by paying ({1} magic symbol) ({R} magic symbol) ({W} magic symbol) ({B} magic symbol) plus commander tax, if applicable.
When Jirina enters the battlefield, it and Mana Echoes trigger.
Resolve the Jirina trigger, creating a 1/1 Human Soldier creature token for each time you've cast Jirina from the command zone this game.
When the Human Soldiers enter the battlefield, Mana Echoes triggers that many times.
Resolve the first Mana Echoes trigger, adding ({C} magic symbol) for each Human and Soldier you control.
Repeat step 5 for each remaining Mana Echoes trigger created in steps 2 and 4.
Activate Phyrexian Altar twice by sacrificing Jirina and a Human Soldier, adding ({R} magic symbol) ({W} magic symbol) .
Choose to return Jirina to the command zone from your graveyard.
If you control a Human Soldier, activate Phyrexian Altar by sacrificing a Human Soldier, adding ({B} magic symbol) .