A powerfull warlord, in charge of most of a planet in another realm, would be eager for another world to control. His chief mage would study and work out how to create and control two way portals to other worlds.
After about a dozen attempts, the mage would get it right, and he would go through it with 5 armored warriors to scout the area.
The portal would appear in a warehouse filled with weapons.I would be part of an arms smuggling group, and would drive into the warehouse, unaware that the scouting force was inside.
I would put up a fight, maybe kill two of the mages protective detail, but i would be captured, brought back with them and questioned by them.
The mages world would be a mix of medieval and magic, perhaps there would be a resistance to the warlord, and they manage to bust me out.
The warlord would want to know our level of technology, population, things like that.
If this appeals to anyone, let me know