The limitations of his physical hardware made it somewhat demanding for him to sustain the vitality of an entire continent like a World Beast.
After all, he was a human, not a gigantic creature like a World Beast. Could he learn to sustain a continent's vitality like a World Beast?
No matter how much life force he generated with each breath, it couldn't surpass Zheng Yichen's Earth's Protection, let alone manage!
The Earth's Protection feature merely enhanced regenerative ability, strength, and defense.
Regenerative ability primarily aids in healing injuries, not primarily in restoring life force. The regenerative ability produced by Earth's Protection is centered on Life Power, which, with just one more word, becomes entirely different in nature from life force.
His normal breathing produced life force; missing a word, it became superior to the one with more words.
