Fantasy: Reborn as a Fake Eunuch in the Enemy's Palace!

[The devil respects life + decisive killing + invincible blood + reverse attack and ascend to immortality] Suppressing a demon king, he was attacked and killed by a team of people. Who would have thought that he would be reborn in the palace of his mortal enemy! The demon king is making a strong comeback! Obtain the most precious desolate tower that imprisons the 'evil fairy', and obtain endless immortal magic from the desolate tower! Take a road to immortality that no one has walked in thousands of years!