[BlazeKing]

Quote:

Originally Posted by Androzani84

Even after seeing this thing up close, I cannot tell how the hell it works.

Since Actar already described how the device works, I'll tell you how the device works (in-story, of course):

Since Hiromi already unleashed his inner demon (the Rex that Revice defeated) and doesn't have one to use, he has to use another way to transform that's different from the other two riders.
Enter, the Demons Driver; an artificial "host" system used to draw out the Spider demon from the ViStamp. The 1st stamping is to draw out the demon and the 2nd stamping is to enter the "contract" like the MOTW now does. It's awesome, imo!