this.addAbility(new HideawayAbility(this));
// {tap}: Add {U} to your mana pool.
this.addAbility(new BlueManaAbility());
// {U}, {tap}: You may play the exiled card without paying its mana cost if a library has twenty or fewer cards in it.
Ability ability = new ActivateIfConditionActivatedAbility(
Zone.BATTLEFIELD, new HideawayPlayEffect(), new ManaCostsImpl("{U}"), new CardsInAnyLibraryCondition(Condition.ComparisonType.LessThan, 21));
ability.addCost(new TapSourceCost());
this.addAbility(ability);
}