// +1: Until your next turn, whenever a creature deals combat damage to Vraska the Unseen, destroy that creature.
this.addAbility(new LoyaltyAbility(new VraskaTheUnseenGainAbilityEffect(new VraskaTheUnseenTriggeredAbility()),1));
// -3: Destroy target nonland permanent.
LoyaltyAbility ability = new LoyaltyAbility(new DestroyTargetEffect(), -3);
ability.addTarget(new TargetNonlandPermanent());
this.addAbility(ability);
// -7: Put three 1/1 black Assassin creature tokens onto the battlefield with "Whenever this creature deals combat damage to a player, that player loses the game."
this.addAbility(new LoyaltyAbility(new CreateTokenEffect(new AssassinToken(), 3), -7));
}