Mu Yuan placed the Great Sage Witch on the surface of the Land of the Undead for several reasons.
First, the existence of the Great Sage Witch is only known to the Silent Sovereign, maintaining its value as a strategic trump card.
Second, the resurrected Great Sage Witch, compared to the Silent Sovereign, is like an irresistible bait, carrying infinite temptation even to Saint Realm Lords.
The Silent Sovereign, for that sliver of hope, will undoubtedly pour more power—even exhaust all its strength—to assist the Land of the Undead.
"We didn't really deceive this Lord. After all, this is a win-win situation!"
The Silent Sovereign has the chance to see old friends and loved ones resurrected; meanwhile, Tianyuan City gains a top-tier worker. Everyone benefits.
Perfect!
Apart from the channel through the Silent Sovereign, it would be virtually impossible for them to acquire genuine Holy Realm Relics.