Invincible Defense at the Start

After traveling through time, Qin Xuan accidentally awakened the system. As a special version of "Master-Apprentice Development", the system thoughtfully provides the "Invincible Defense" feature. That is, no matter what kind of attack Qin Xuan suffers, no matter what level of power he reaches, it will not have the slightest impact on him. As a price, its attack power... Basically stays at the level before time travel. So, relying on invincible defense, Qin Xuan embarked on the road of cultivating apprentices (×) and girls (√) while preaching and solving doubts (×) and fooling around (√). Incidentally, turning the whole world upside down. PS: Overall, this is a work with bad taste (×) and positive energy (√).