// until this creature leaves the battlefield."
Ability ability = new EntersBattlefieldTriggeredAbility(new ConstrictingSliverExileEffect(), true);
ability.addTarget(new TargetCreaturePermanent(filterTarget));
ability.addEffect(new ConstrictingSliverAddDelayedReturnEffect());
this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD,
new GainAbilityAllEffect(ability,
Duration.WhileOnBattlefield, new FilterControlledCreaturePermanent("Sliver","Sliver creatures"),
"Sliver creatures you control have \"When this creature enters the battlefield, you may exile target creature an opponent controls until this creature leaves the battlefield.\"")));
}