Perhaps that Magus was dropped into the RD time line, since it obviously wasn't either home or another world? I just can't seem to accept the fact that it makes it seem like Magus was going to be involved in something, but the writers just go 'BWAHAHAHAHA, you will never know what will happen to poor old Magus!' That would just be silly.

And even if that event did happen in the current timeline, it doesn't seem to show how Schala could have been the one to orchestrate the events of Trigger.

To begin, the Time Devourer exists only because Lavos forsaw these kids could defeat him, as you learn in Chronopolis.

However, under the theory it was Schala's doing, that can only be the case If the Time Devour/Dream Devour existed.

Just like my old Idea that it was the doing of Fate, you are creating a time loop to make it all happen. The very portals created by Schala couldn't exist without Lavos feeling threatened by Crono and gang, but Crono and Gang cannot become a threat without the portals made by Schala.

Its really an unnescessary Time Paradox,