Oaken, The Harbinger

Trample, Oaken, the Harbinger has power and toughness equal to the number of lands you control.
At the beginning of your endstep you may put 4 +1/+1 counters on up to one target land you control. That land becomes an Elemental creature that's still a land.
Once per turn on your turn you may cast a creature with mana value less than or equal to the number of creatures you control without paying its mana cost