this.color.setRed(true);
this.power = new MageInt(3);
this.toughness = new MageInt(3);
// All Slivers have "{tap}: Target Sliver creature gets +X/+0 until end of turn, where X is the number of Slivers on the battlefield."
Ability ability = new SimpleActivatedAbility(Zone.BATTLEFIELD, new BoostTargetEffect(new PermanentsOnBattlefieldCount(new FilterCreaturePermanent("Sliver", "Sliver creatures")), new StaticValue(0), Duration.EndOfTurn), new TapSourceCost());
Target target = new TargetCreaturePermanent(new FilterCreaturePermanent("Sliver", "Sliver creature"));
ability.addTarget(target);
this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new GainAbilityAllEffect(ability, Duration.WhileOnBattlefield, new FilterCreaturePermanent("Sliver", "Sliver creatures"))));
}