Transferring to Another Dimension and Summoning Heroic Spirits

After a catastrophe, the earth fell into a doomsday crisis. In order to resist this doomsday crisis, humans summoned servants to fight against invaders from other dimensions. However, all of this is just the setting of a novel written by a time-traveling author. This book is a slow-burning one, with not many exciting points at the beginning. I found that my first two novels had the same problem, that is, the text was wrong. It was clearly about transformation, but in the end it became a summons. This time I wrote about summons directly, without using transformation. This book is a doomsday stream in the early stage, and an infinite stream in the middle and late stages. Without a heroine, you can treat the servants as a harem. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.