Undercover Demon: I Become a System and Bewitch the World

As a mole among the Heavenly Demons, you have to act more loyal than anyone else.

And the way to show loyalty to the Heavenly Demons is to make living beings feel ecstasy and agony, and fall into demonic ways...

Wait? Ecstasy and agony?

Is there anything that can make living beings feel more ecstasy and agony than the tropes of web novels?

So he transformed into a System and hid inside living beings...

Your aptitude is poor, and cultivating is difficult?

No problem. Here's a stat-boosting System, and you'll take off in no time!

You're a coward and want to lie low until you're invincible?

Stop dawdling. Here's an auto-play System. Now get out there and make waves!

You shout, "Thirty years east of the river, thirty years west of the river"?

Try the sign-in System. Face-slapping your rivals doesn't have to wait until tomorrow!

At last, after Chen Xuan possessed and devoured one native after another, along with Heavenly Demons who thought they were transmigrators,

he had nearly everyone on both the righteous and demonic sides under his control.

His own cultivation had also reached its peak.

Until...

The Demon Ancestor said tearfully, "Please welcome the new Demon Ancestor, Chen Xuan!"

The Dao Ancestor said bitterly, "Chen Xuan, please show mercy to the Heavenly Dao!"