Liu Chen transmigrates into the body of an impoverished member of the imperial clan in Yingchuan at the end of the Han dynasty.
The roof leaks and the walls are cracked. They have barely half a sack of grain, and the Yellow Turban Rebellion is only a month away.
The good news is that he awakens the Heroes Summoning System. Summon someone like Han Xin, Li Jing, Yue Fei, or Li Yuanba, and he can dominate the land.
But there's bad news, too:
The System has a balancing mechanism called the Heroes Register.
For every hero you summon, it sends several others into the world. They might be regional strongmen like Dou Jiande or Wang Shichong, or emperors like Qin Shi Huang and Li Shimin, who come fully supplied.
They don't answer to you, and they don't recognize you as their lord.
They're warlords in their own right.
So the Three Kingdoms, originally a struggle between Cao Cao, Liu Bei, and Sun Quan, becomes a great battle royale among emperors from across history:
Qin Shi Huang restores the Qin dynasty in Guanzhong, Li Shimin founds a new Tang dynasty in Hebei, and Liu Xiu revives the Han in Nanyang...
Looking at the map full of fellow transmigrators, Liu Chen falls into deep thought:
“I just wanted to lie low and build up my strength. How did the world suddenly end up full of these old ancestors?”
[Also known as: The Three Kingdoms: Summoning the Ultimate Tryhards; Emperors from All of History Fight Me for My Territory; How to Survive Caught Between Qin Shi Huang and Li Shimin]
[Reader advisory]: The protagonist is not invincible, the System doesn't hand out gifts for free, and emperors cannot be summoned. You can only defeat them or make them submit.
[Click to claim]: Cheng Yaojin (combat strength 92, comes with his signature three-axe technique, delivered to your door, with one Fang Xuanling included free)
No one has commented, so I'll make one myself.