Mongke was not surprised by these words. He wanted to enter the Battle Taboo Realm, and since that involved achieving Paragon Strength, he thought of using his clone ability. He would use countless resources to condense a Paragon Tier Clone before condensing it into a Giant Heart to absorb.
The idea is sound and foolproof. The Giant Heart should push Mongke's strength to the level of Paragon. However, after creating this technique, he realized his method was wrong. The final result of fusing with that heart will be his death through explosion. His body cannot bear the power/energy of that heart.
He would need to open the Gate of Flesh to bear its power, but doing so would contradict his desire to enter the Battle Taboo Realm. "So, what do you think?" Mongke asked.
"You're missing the crux of entering the Battle Realm," Wang Wei said, thinking how to explain his thoughts best.