All permanents on the battlefield (Tarmogoyf Nest attached to any land you control without summoning sickness).
Creatures you control can tap to produce at least ({1} magic symbol) ({G} magic symbol) .
Druid Class is level 2.
Steps
Activate Druid Class's third ability by paying ({4} magic symbol) ({G} magic symbol) , causing it to become level 3, and causing the land with Tarmogoyf Nest attached to become a creature.
Activate any number of creatures you control by tapping them, adding at least ({1} magic symbol) ({G} magic symbol) .
Activate the land with Tarmogoyf Nest attached by paying ({1} magic symbol) ({G} magic symbol) and tapping it, creating a Tarmogoyf creature token.
When the Tarmogoyf enters the battlefield, Intruder Alarm triggers, untapping all creatures.