First I would like to start out by saying the Developer that designed the Forbidden Crypt really spoiled us. The combination of different elements really led to an extremely fun board. I would like to propose using that combination to create a new home for Vyx with as little resources as possible. So here is my suggestion:
1) Entrance: A public entrance through a portal in the new Shadow 'Towne'. These could be joined but not hosted.
2) Board: Board could be any of the Shadow caves depending on how many possible Vyxnaars the devs would like to see.
3) Mobs: The common mobs would be the same ones in the caves, though they would be respawning.
4) Bosses: All current bosses, including Shadow Djinns would be replaced by 'a chance for Vyxnaar to spawn there'.
5) Spawn Rate: He would have a random timer based spawn rate similar to the one in the Forbidden Crypt.
6) Regular Pink Drop Rate: Regular pink shadow helms would have a drop rate of 10% of their current shadow cave drop rate.
7) Vyxnaar Helm Drop Rate: 10% of the Vyx shadow helm drop rate, or 1 percent of current shadow cave drop rate. Of course these rates are just toss outs, but the idea is for it to be a rare drop from a common spawn, not a common drop from a rare spawn.

Let me know what you all think.