He followed Amber in and thought about what he was going to say. I enchant this rock to turn into a small glass cage, with a lid on top. whoever enters there shall never die or be uncomfortable for the duration of their stay. That sounded about right, but Djinn was unsure on the specifications size... half the size of the desk sounds appropriate. Taking a deep breath, he picked up a loose rock from the ground and walked over to an empty area near a small mud wallow*, which he assumed was Amber's sleeping place.
"I enchant this rock to turn into a glass cage half the size of this desk," he gestured at it, "with a lid on the top. I enchant it so that whoever enters it shall never die or be uncomfortable for the duration of their stay."
*Unless Amber doesn't sleep in a mud wallow. You know, whatever she's most comfortable with.