Knightfall
World of Kulan DM
The double doors are made out of strong wood that is unknown in Bluffside and the Northwest region. The doors, when first encountered, seemed mundane (but ornate *). While one or both of the doors are open, there is no visible magical or psionic effects on the doors. It is only when they are completely closed, that the glowing psionic script appears on them.
The doors have handles like this image (no metal loops) and the doors open inward into the labyrinth. There are handles on both sides of the doors. While the doors have ornate carvings on them, those additions to the door are subtle. There are no protrusions sticking out from the double doors.
I admit I didn't really think about what was designed on the doors. So...
On the edges of the two doors, there is iconography related to the outer planes (but not the Unseen Abyss), as well as the Shadowstar Sea, which is the plane on which The Ancients travelled to reach Kulan for the first time (common scholarly knowledge). Kulan's solar system is laid out on the door with Kulan's sun in the centre. Kulan's solar system has the same number of planets as our solar system, but Kulan has two full-sized moons instead one for Earth. (Kulan's moons are known as Novan and Lithe.)
When the PCs first encountered the double doors (before Vitus was with the group), the doors were open and seemed more mundane. The PCs now know the doors are powerfully psionic creations (akin to a psionic item). The phrase that appears on the doors must be spoken to enter the demiplanar dungeon, but a version of the phrase can be spoken from the other side to open them from inside the Labyrinth of Lost Souls.
A DC 20 Spellcraft (or DC 10 Psicraft) check is required to block out the mad whisperings that constantly emanate from the doors. This protection isn't permanent, especially when interacting with the door. Rockhorn is dealing with that right now.
Other than speaking the psionic phrase, there is no other known "key" to enter or exit the Labyrinth of Lost Souls. If there is a way to permanently sea off the labyrinth, the only beings who truly knows is either the Living Altar or the Mad Soul.
Falen did mentally ask Ting for a possible solution, but I don't believe @Aust Thale has conveyed that information to the other PCs, yet. While Ting was mentally in contact with Falen, some of the conversation spilled over to those around them, so Vitus might have heard parts of what Falen learned (the hidden text) since he was so close.
It would be a DC 20 Will saving throw for Vitus to open up his mind completely to that mental conversation. To do so risks his mind, however. If you fail the save by 5 or more, you take the same 2 points of damage that Ting takes from the machinations of the Mad Soul. If you roll a 1, then add another 6 points of damage.
Knightfall Request: 2d6 Roll: [4, 2] = 6
Reason: Extra damage that Vitus might take from opening up his mind to Ting (and the Mad Soul)
If you make the save, you can read the hidden text meant for Aust Thale in the post linked above. Also...
Regardless of the save's results, you can roll Knowledge checks for Vitus to allow him to dig into the mental knowledge flowing between Falen and Ting and the Mad Soul. If you rolled a 1 on the save, then the checks are at -4. If you failed the save by 5 or more, then the checks are at -2. If you made the save, roll the checks as normal. And, if you roll a Natural 20 on the save, you can add +4 to the Knowledge checks.
House Rule Reminder! Rolling a 1 on a skill check reduces the result by -10 while rolling a Natural 20 on a skill check increases the result by +10. This is only for skill checks, not for saves or attack rolls.
* An DC 20 Appraise check would give you the approx. value of the doors.
