Most game dungeons are leveled so the PC is challenged. A 1st level PC faces wimpy monsters, and gets wimpy treasure. Higher get tougher opponents and greater treasure. If that system is used here, our archmage may well be afraid to enter the dungeon, and also afraid that those that do enter might exit too strong for him to handle.
With this teleport system, do people HAVE to enter via the main gate or can some of these "sponsored" teams use a teleport point that someone else left behind?
The tattoos they get are what allow them to go through the portals and back again. They can't go back through other people's portals because they didn't go through it in the first place and the tattoo wouldn't react to it.
Well, there had to be some sort of reason this little portal had not been overrun by neighboring powers. There's no way any kingdom would normally ignore a potential treasure trove like that.
The word "potential" could be key here. A lot of adventurers die here, and that somewhat balances the riches the survivors get. And the treasure trove, tho huge on a personal basis, is only a few people a day, and so is likely petty cash on a kingdom scale. So the nations might well hesitate until they knew of a sure way to loot the place.
Recall too that war is expensive, even if you win. And most lose. So if you have, say, 4 kingdoms each wanting Marblegate, the costs of gaining it, if you can, are not nearly as much as the profits from sharing it.
Now the banker may believe what we read, and the archmage may peddle the same version for his own purposes, but the kingdoms may not be that eager to war over the gate.
Of course, if they thought they were sure to win... or were scared that somebody else did...
Recall too that war is expensive, even if you win. And most lose. So if you have, say, 4 kingdoms each wanting Marblegate, the costs of gaining it, if you can, are not nearly as much as the profits from sharing it.
Now the banker may believe what we read, and the archmage may peddle the same version for his own purposes, but the kingdoms may not be that eager to war over the gate.
Of course, if they thought they were sure to win... or were scared that somebody else did...
Like anything is simple in politics