Elite Arcanist on the battlefield (without summoning sickness).
Great Train Heist in exile (exiled by
Elite Arcanist).
Notable Prerequisites
Creatures you control can tap to produce at least ({3} magic symbol) ({R} magic symbol) .
Steps
Activate any number of creatures by tapping it, adding at least ({3} magic symbol) ({R} magic symbol) .
Activate
Elite Arcanist by paying ({1} magic symbol) and tapping it, copying
Great Train Heist and casting the copy without paying its mana cost, and choosing to pay ({2} magic symbol) ({R} magic symbol) to select its first mode.
Resolve the copy of
Great Train Heist, untapping all creatures you control and get an additional combat phase if it is currently a combat phase.
Repeat.
Results
Infinite storm count.
Infinite combat phases.
Infinite untap of creatures you control.
Infinite mana creatures you control can produce.
Infinite magecraft triggers.
Infinite power for creatures you control until end of turn.