Feeling the boost the Castle of the Undead brought him, he also understood just how twisted the existence of such a thing from the Sea of Realms was when it appeared in the real world.
Just thinking about the battle power boost he would get within this castle once he had full control over the Castle of the Undead made Zi Liyuan break out in a cold sweat on his forehead.
"Thankfully, Andrew is dead. He's only left with a residual soul and body, unable to fully unleash the might that the Castle of the Undead could grant him. Otherwise, from the moment we stepped into the Castle of the Undead, we would've been done for. Xiao Yurou would have had to prepare our memorial tablets."
Not to mention having prepared the Minor Forbidden Spell "Death Storm" in advance through the Death Magic guild, maintaining a constant flow of death energy alone could easily annihilate an Epic Boss.