Before they entered, Krune found where that Core Formation Realm demon beast was and threw him a pill. That was the Shell Repairing Pill that Dilo used to heal his Dantian in the past. Krune then told him with a Divine Sense.
"This pill of mine is quite overbearing. So make sure to have a lot of spirit stones available once you swallow it."
Fortunately for that Demon Beast, he still had a few spirit stones from the rewards in that Mountain Bubble Realm. Although they were just leftovers from the battles for the resources, it was still a lot for a Core Formation Realm like him.