// Ghave, Guru of Spores enters the battlefield with five +1/+1 counters on it.
this.addAbility(new EntersBattlefieldAbility(new AddCountersSourceEffect(CounterType.P1P1.createInstance(5))));
// {1}, Remove a +1/+1 counter from a creature you control: Put a 1/1 green Saproling creature token onto the battlefield.
Ability ability = new SimpleActivatedAbility(Zone.BATTLEFIELD, new CreateTokenEffect(new SaprolingToken()), new GenericManaCost(1));
ability.addCost(new RemoveCounterCost(new TargetControlledCreaturePermanent(), CounterType.P1P1));
this.addAbility(ability);
// {1}, Sacrifice a creature: Put a +1/+1 counter on target creature.
Ability ability2 = new SimpleActivatedAbility(Zone.BATTLEFIELD, new AddCountersTargetEffect(CounterType.P1P1.createInstance()), new GenericManaCost(1));
ability2.addCost(new SacrificeTargetCost(new TargetControlledPermanent(filter)));