Comment by Just Love To Read on Abhinaya Apuri

So what exactly happened here is that the phone used by Seoyoon (the fake saintess) could make her travel from the 2 diff dimensions (Korea and Stern Empire). Everytime she traveled between the 2 dimensions her rank as a guide would go up. However, there's a price to pay for every travel she made. She would always received a warning message whenever she tried to travel dimension. Mtl was crappy but from what I can understand the warning states that to travel she must follow the law of equivalent exchange. She'll be bringing something from earth equivalent to her gaining a higher rank. Meaning for every travel, a monster wave from Earth would also travel dimension to Stern Empire and eveytime she gained ranks, higher ranks of monsters would come in wave.