Lu Yin threw Star Energy Marrow into the pile and watched the needle's value climb bit by bit, at a loss for words. It wasn't nearly as outrageous as the Slippers, but even so, it took close to a hundred billion to raise it by one level. The needle could already pierce a Semi-Progenitor's Inner World. If he upgraded it, could it threaten a Progenitor?
He wasn't sure. He'd wanted to give it a try, but then he remembered the Slippers.
Whether or not the needle could reach the Slippers' destructive power after an upgrade was beside the point. The damage the Slippers could inflict on the mist had already reached its limit. Even if he upgraded the needle, it wouldn't do any more damage to the mist. In other words, it would be completely useless for releasing Mist Ancestor.
Lu Yin shook his head, put the needle away, and checked his collection again. The Years Withered Wood could be upgraded, and so could the Nether River, but the cost would be enormous. There was also the Myriad Beast Cage's metal—the Devourer that had once brought disaster to the Fourth Continent.
Back then, upgrading a piece of it had cost close to six billion cubic meters of Star Energy Marrow. It had given that piece of Devourer an instinct to devour flesh and blood, and destructive power approaching that of a Star Envoy. Lu Yin was sure that if he let it loose and didn't deal with it in time, it would eventually become a disaster all over again.
And if he upgraded it himself, it would become terrifying without even needing to devour flesh and blood.
He would definitely give this thing to someone someday, but there was no need to upgrade it yet.
Right, he'd almost forgotten about