Ísar let go of his uncle's hand once they'd successfully transported to the path leading to the tomb.
Sneaking out hadn't been a problem, it was being able to transport there that had worried Ísar somewhat. Transportation was an easy spell to learn in theory, not so much in practice, and there were usually limits. Distance was one, magical reserve another, and also knowing the location beforehand. It was why Osayi's ability to teleport anywhere in the world, at anytime, was something that inspired awe in Ísar.
Poorly executed teleportation was also dangerous. There were past cases of bodies being dismembered.
He was surprised to find out that his uncle was not only to teleport properly, but was actually a fairly formidable magic user. Records only showed how painstakingly average the old man was at everything, but Ísar was starting to distrust the castle's records more and more as time passed.