The one who invited him was, naturally, the Three-Eyed Heavenly Monarch.
Old Daoist Wangchen had not originally wanted to come. Even a powerhouse like the Three-Eyed Heavenly Monarch could not handle this entity, so even with his own help, it was unlikely they would succeed. However, he had no choice. The Three-Eyed Heavenly Monarch offered too much—so much that Old Daoist Wangchen had no reason to refuse.
Furthermore, Old Daoist Wangchen had recently acquired a wooden carving. It was incredibly powerful, capable of exerting combat strength comparable to a Semi-Saint. With this carving in hand, plus himself and the Three-Eyed Heavenly Monarch, it would be equivalent to three Semi-Saints working together. Unless their opponent was a true Saint, there was no reason they wouldn't win.
Chapter 449