text: The emblem given to you by Tibalt allows you to play cards exiled with that specific Tibalt, Cosmic Impostor, even after that Tibalt leaves the battlefield. If a different Tibalt, Cosmic Impostor comes under your control, it's a new object (even if it's represented by the same card). Of course, the new Tibalt will also give you an emblem so you can play the cards he exiles.