: Exile target enchantment, tapped artifact, or tapped creature. : Search your library for an artifact or creature card, put it onto the battlefield, then shuffle your library. It gains haste. Return it to your hand at the beginning of the next end step.
You can activate Nahiri’s first ability with no intention of discarding a card just to add loyalty to Nahiri.
If you find a noncreature artifact with Nahiri’s third ability, it will still gain haste, even though it won’t be meaningful unless that artifact becomes a creature.
If the artifact or creature put onto the battlefield with Nahiri’s third ability leaves the battlefield before the next end step, it won’t be returned to your hand from its new zone.