I'm looking for this bl manhwa that i vaguely remember reading wasn't sure if it was chine...

I'm looking for this bl manhwa that i vaguely remember reading wasn't sure if it was chinese or korean but it's about this ordinary guy chosen by the water dragon or emperor??? And then turns out he's also like a powerful being IDK I FORGOT THE PLOT SORRY BUT IF ANYONE CAN LIKE REPLY ANY MANHWA THAT HAS A PLOT LIKE THAT LMK THANKSSS