Vitrysil, The Multiverse Tree

Vitrysil can be your commander.
{t}: Add {g} to your mana pool. If Vitrysil is your commander and that mana was spent on a green spell, it can't be countered. If that spell was a creature spell, it enters the battlefield with a growth counter on it.
Permanents you control with growth counters on them are forests in addition to their other types.At the beginning of your end step, if you control 5 or more permanents with growth counters on them, transform Vitrysil.