Put a +1/+1 counter on target creature you control, then double the number of +1/+1 counters on each creature that had a +1/+1 counter put on it this way.

Overload (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Trample

Kalonian Hydra enters with four +1/+1 counters on it.

Whenever Kalonian Hydra attacks, double the number of +1/+1 counters on each creature you control.

Kalonian Twingrove's power and toughness are each equal to the number of Forests you control.

When Kalonian Twingrove enters, create a green Treefolk Warrior creature token with "This creature's power and toughness are each equal to the number of Forests you control."