this.color.setBlue(true);
this.power = new MageInt(4);
this.toughness = new MageInt(4);
// Champion a Merfolk
this.addAbility(new ChampionAbility(this, "Merfolk"));
// Whenever Wanderwine Prophets deals combat damage to a player, you may sacrifice a Merfolk. If you do, take an extra turn after this one.
Ability ability = new DealsCombatDamageToAPlayerTriggeredAbility(new AddExtraTurnControllerEffect(), true);
ability.addCost(new SacrificeTargetCost(new TargetControlledPermanent(1, 1, filter, true)));
this.addAbility(ability);