I think that would be the Wristpocket cantrip that we later see Scanlan use. If I remember right, he said that Kaylie was the one who taught it to him. Sam posted the information for the cantrip on Reddit a while back: link
Edit: I figure I should probably just post the info here as well:
Wristpocket Conjuration Cantrip Casting Time: 1 action Range: Self Components: S Duration: Instantaneous You flick your wrist with a flourish, causing a single object that weighs no more than 5 lbs that you hold within your hand to vanish. The object is actually transported and stored within a small extradimensional pocket plane. The object remains there indefinitely until this cantrip is cast again, upon which it is immediately transported back into your grasp. You cannot store an object while one already occupies the extradimensional pocket.