Marwyn has power 4 or greater and has at least a +1/+0 boost from secondary effects.
Steps
Activate Marwyn by tapping it, adding at least ({G} magic symbol) ({G} magic symbol) .
Cast Wirewood Symbiote by paying ({G} magic symbol) .
Activate Mirror Entity by paying ({1} magic symbol) , giving creatures you control all creature types and base power and toughness 1/1 until end of turn.
Activate Wirewood Symbiote by returning it from the battlefield to your hand, untapping Marwyn.
Repeat.
Notes
Once you have infinite mana, you may activate Mirror Entity to make your creatures infinitely large until end of turn.
Results
Infinite LTB.
Infinite ETB.
Infinite storm count.
Infinite green mana.
Infinitely large creatures you control until end of turn.