How to use

PhaseInTriggeredAbility

in

mage.abilities.common

@Override
public PhaseInTriggeredAbility copy() {
  return new PhaseInTriggeredAbility(this);
}

@Override
public boolean checkTrigger(GameEvent event, Game game) {
  return getSourceId().equals(event.getTargetId());
}

public ShimmeringEfreet(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId, setInfo, new CardType[]{CardType.CREATURE}, "{2}{U}");
  this.subtype.add(SubType.EFREET);
  this.power = new MageInt(2);
  this.toughness = new MageInt(2);
  // Flying
  this.addAbility(FlyingAbility.getInstance());
  // Phasing
  this.addAbility(PhasingAbility.getInstance());
  // Whenever Shimmering Efreet phases in, target creature phases out.
  Ability ability = new PhaseInTriggeredAbility(new PhaseOutTargetEffect(), false);
  ability.addTarget(new TargetCreaturePermanent());
  this.addAbility(ability);
}

public WarpingWurm(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId, setInfo, new CardType[]{CardType.CREATURE}, "{2}{G}{U}");
  this.subtype.add(SubType.WURM);
  this.power = new MageInt(1);
  this.toughness = new MageInt(1);
  // Phasing
  this.addAbility(PhasingAbility.getInstance());
  // At the beginning of your upkeep, Warping Wurm phases out unless you pay {2}{G}{U}.
  this.addAbility(new BeginningOfUpkeepTriggeredAbility(
      new DoUnlessControllerPaysEffect(
          new PhaseOutSourceEffect(),
          new ManaCostsImpl("{2}{G}{U}")
      ).setText("{this} phases out unless you pay {2}{G}{U}"),
      TargetController.YOU, false
  ));
  // When Warping Wurm phases in, put a +1/+1 counter on it.
  this.addAbility(new PhaseInTriggeredAbility(new AddCountersSourceEffect(CounterType.P1P1.createInstance()), false));
}