this.color.setGreen(true);
this.power = new MageInt(2);
this.toughness = new MageInt(3);
// Whenever another green creature enters the battlefield under your control, put a +1/+1 counter on target creature.
Ability ability = new EntersBattlefieldAllTriggeredAbility(
Zone.BATTLEFIELD,
new AddCountersTargetEffect(CounterType.P1P1.createInstance()),
filter, false, null, true);
ability.addTarget(new TargetCreaturePermanent());
this.addAbility(ability);
}