You control a creature, artifact, or land that can produce at least ({2} magic symbol) .
Yenna does not have summoning sickness.
Steps
Activate the mana-producing permanent by tapping it, adding at least ({2} magic symbol) .
Activate Yenna by paying ({2} magic symbol) and tapping it, creating a token copy of Nature's Chosen attached to Yenna, untapping Yenna, and scrying 2.
Activate the Nature's Chosen token's second ability by tapping Yenna, untapping the mana-producing permanent.
Activate the Nature's Chosen token's first ability by paying ({0} magic symbol) , untapping Yenna.
Activate Phantatog's first ability by sacrificing the Nature's Chosen token, causing Phantatog to get +1/+1 until end of turn.
Repeat any number of times.
If the mana-producing permanent can produce at least ({3} magic symbol) , this combo produces infinite mana that artifacts, creatures, and lands you control can produce.
Results
Infinitely large Phantatog until end of turn.
Infinite mana lands, artifacts, and creatures you control can produce.