How to use

Heal

in

mage.cards.h

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

public Heal(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId,setInfo,new CardType[]{CardType.INSTANT},"{W}");
  // Prevent the next 1 damage that would be dealt to any target this turn.
  // Draw a card at the beginning of the next turn's upkeep.
  this.getSpellAbility().addEffect(new PreventDamageToTargetEffect(Duration.EndOfTurn, 1));
  this.getSpellAbility().addEffect(new CreateDelayedTriggeredAbilityEffect(new AtTheBeginOfNextUpkeepDelayedTriggeredAbility(new DrawCardSourceControllerEffect(1)), false));
  this.getSpellAbility().addTarget(new TargetAnyTarget());
  
}

 Mage fireMage = new Mage("Red Niminim");
fireMage.addSpell(new Fireball());
fireMage.addAttribute(Attribute.RESIST_FIRE);
fireMage.addAttribute(Attribute.WEAK_TO_COLD);

Mage iceMage = new Mage("Blue Niminim");
fireMage.addSpell(new Icestorm());
fireMage.addAttribute(Attribute.RESIST_COLD);
fireMage.addAttribute(Attribute.WEAK_TO_FIRE);

Cleric cleric = new Cleric("Friar Joe");
cleric.addSpell(new Heal());

// battle!

fireMage.castSpell("Fireball", cleric);     // 15 damage
fireMage.castSpell("Fireball", iceMage);    // 30 damage
fireMage.castSpell("Fireball", fireMage);   // 0 damage

iceMage.castSpell("Icestorm", cleric);      // 15 damage
iceMage.castSpell("Icestorm", fireMage);    // 30 damage
iceMage.castSpell("Icestorm", iceMage);     // 0 damage

cleric.castSpell("Heal", cleric);           // 15 healed