I wouldn't call it a time travel spell in Tactics, they're casting Warp. Calling upon what is referred to as the Reeve (magistrate, ruler) of Time to throw wide the gates and open a portal from Orbonne to Mullonde. Nothing suggests time travel like that, there are no plot factors of it as time travel, so much as the interplay of Space and Time and crossing a great distance in an instant is technically time travel.