How to use

RevealTargetPlayerLibraryEffect

in

mage.abilities.effects.common

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

public RevealTargetPlayerLibraryEffect(DynamicValue amountCards) {
  super(Outcome.Neutral);
  this.amountCards = amountCards;
  this.staticText = setText();
}

public AvenWindreader(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId,setInfo,new CardType[]{CardType.CREATURE},"{3}{U}{U}");
  this.subtype.add(SubType.BIRD);
  this.subtype.add(SubType.SOLDIER);
  this.subtype.add(SubType.WIZARD);
  this.power = new MageInt(3);
  this.toughness = new MageInt(3);
  // Flying
  this.addAbility(FlyingAbility.getInstance());
  // {1}{U}: Target player reveals the top card of their library.
  Ability ability = new SimpleActivatedAbility(Zone.BATTLEFIELD, new RevealTargetPlayerLibraryEffect(1), new ManaCostsImpl("{1}{U}"));
  ability.addTarget(new TargetPlayer());
  this.addAbility(ability);
}