({8} magic symbol) ({2R} magic symbol) ({2R} magic symbol) ({2R} magic symbol) ({2R} magic symbol) at most available.
Steps
Activate
Improvised Arsenal by paying ({4} magic symbol) ({R} magic symbol) , creating a token copy of it.
Chishiro triggers, creating a creature token.
When the creature token enters,
Mana Echoes triggers, adding ({C} magic symbol) for each creature you control that shares a creature type with the creature token.
If needed, activate
Urn of Godfire by paying ({2} magic symbol) , adding ({R} magic symbol) .
Repeat.
Notes
The mana cost can be reduced if you control more creatures that share type(s) with the created tokens as the combo begins. You should perform step 4 only if you have no ({R} magic symbol) in your mana pool. With infinite mana, the
Improvised Arsenal tokens can be attached to creatures you control to make them infinitely large.
Results
Infinite ETB.
Infinite colored mana.
Infinite colorless mana.
Infinite creature tokens that are infinitely powerful.