General Niu Juo's questions were valid since there were other communication jade slips that worked within the Desolate Blood Battlefield too. He had one with him too. After all, that's how he had managed to contact the people outside.
The one that Old Man Lao had given him was several levels above it.
"I'm giving that to you just in case… you end up in another plane. There's no saying with a Transcendent Immortal." Old Man Lao replied.
"You think there'll be a spatial opening?" General Niu Juo asked.
"It is possible. Or maybe it could be a teleportation array, who knows? That Jade Slip will be crucial then. And if you don't end up needing it, just return it to me later." Old Man Lao replied in the end.
Niu Juo was no stranger to spatial travel and other accidents associated with it. He had also been to a few excursions in the past, and knew just how dangerous it could be. In fact, that was his main work.