How to use

ExileTopCardOfGraveyardCost

in

mage.abilities.costs.common

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

public Alms(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId,setInfo,new CardType[]{CardType.ENCHANTMENT},"{W}");
  // {1}, Exile the top card of your graveyard: Prevent the next 1 damage that would be dealt to target creature this turn.
  Ability ability = new SimpleActivatedAbility(Zone.BATTLEFIELD, new PreventDamageToTargetEffect(Duration.EndOfTurn, 1), new GenericManaCost(1));
  ability.addCost(new ExileTopCardOfGraveyardCost(1));
  ability.addTarget(new TargetCreaturePermanent());
  this.addAbility(ability);
}

public NaturesKiss(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId,setInfo,new CardType[]{CardType.ENCHANTMENT},"{1}{G}");
  this.subtype.add(SubType.AURA);
  // Enchant creature
  TargetPermanent auraTarget = new TargetCreaturePermanent();
  this.getSpellAbility().addTarget(auraTarget);
  this.getSpellAbility().addEffect(new AttachEffect(Outcome.BoostCreature));
  this.addAbility(new EnchantAbility(auraTarget.getTargetName()));
  
  // {1}, Exile the top card of your graveyard: Enchanted creature gets +1/+1 until end of turn.
  Ability ability = new SimpleActivatedAbility(Zone.BATTLEFIELD, new BoostEnchantedEffect(1, 1, Duration.EndOfTurn), new ManaCostsImpl("{1}"));
  ability.addCost(new ExileTopCardOfGraveyardCost(1));
  this.addAbility(ability);
}