Two Cores

"It's finally done!" Krune said as he stared at the Yin Beasts hanging from the ceiling. There were fourteen of them in total. Among them, eight had reached maturity. As for the rest, they were in descending order of maturity, including the fourteenth one that had just been birthed. 

"It's time to reap the benefits," he said soon after as he picked up the Nightmare Core, noticing that it had dimmed considerably when compared to how he obtained it at first. It had expended a lot of power to birth fourteen Yin Beasts. 

Smiling, Krune condensed the Cloud Whale around it, piercing it through the body of the youngest Yin Beast, watching it scream in agony as its essence was extracted. 

Krune smiled in response, watching the degree of increase in the Nightmare Core's strength surpass what he saw previously. "So, absorbing blood from those that are alive is more effective. That trip to the Sub-Realm is proving valuable in countless situations."