Agatha of the Vile Cauldron has power 4 or greater.
Devoted Druid does not have summoning sickness.
You control at least one basic Mountain.
Steps
Activate Devoted Druid's first ability by tapping it, adding ({G} magic symbol) .
Activate a basic Mountain by tapping it, adding ({R} magic symbol) .
Activate Earthcraft by tapping Cinderhaze Wretch, untapping the Mountain.
Activate Agatha of the Vile Cauldron by paying at most ({R} magic symbol) ({G} magic symbol) , giving all other creatures you control +1/+1, trample and haste until end of turn.
Activate Devoted Druid and Cinderhaze Wretch's second abilities by putting a -1/-1 counter on them, untapping them.
Repeat.
Results
Infinitely large creatures until end of turn except Agatha of the Vile Cauldron, Devoted Druid and Cinderhaze Wretch.