The Orthran, the Beast of Blessings

Appearance:

The Orthran is not a single specific creature, it is a dungeon manifestation that is quickly and obviously different, with the common traits being albinism, a docile demeanor, and the fact that whatever base creature it was created from, it now has two heads. The only real caveats to the creation of an Orthran is that they are monsters, have heads, and are not humanoids. There are no two-headed white goblins, or ghosts, or slimes. The original mythic Orthran was a two-headed white wolf.

What is the Secret?

We're not beating around the bush here. Orthrans are gifts from the dungeon, and slaying one grants a major boon. After slaying the Orthran, a glowing light rises from its corpse and flies into the being that slew it, and then the boon hits.

Option 1 - Full Heal, all HP restored

Option 2 - Full Rest, all MP restored

Option 3 - Level Up

Option 4 - Full Restoration

Who Knows?

A few senior members of the heroic guilds are aware of the Orthran, and the Lords of Terrasquestone. The majority of people know almost nothing about them. Seasoned adventurers can trade stories about a friend of a friend who knew a stranger who survived a horrific potential TPK by encountering one, slaying it, getting the rush from it, and then being able to escape with their life.

How has the Secret Remained?

The issue with the Orthran is that they don't appear unless the shit has hit the fan, and the party is in desperate need of a boost, or the party is on the verge of TPK and the boon of the Orthran would let one survivor escape, and then carry out the efforts of resurrection or restoring their friends.

If the boon is lost, or the adventurers fail, corpses don't tell tales.

When a single raving member of a slaughtered party returns talking about how a two-headed dungeon salamander appeared and after killing it they were fully restored, most people tend to treat the emotionally traumatized person with kid gloves. They've had a bad time, and the descriptions vary enough that no one is really putting the information together.

Also, the Lords of Terrasquestone tend to understand that the Orthran are a correcting factor within the dungeon and if they let rumor spread that the dungeon can sometimes spawn such a creature when a party is in over it's head, or hit something they should not have, well recklessly stupid people can make really bad decisions.

Layers

The Orthran are intelligent and seemingly bashful versions of monsters, and make their appearances rarely and briefly. They are also FAST, so if an adventurer ignores them, they quickly escape. They also have a good evasion score, but no armor, and pretty much any damage inflicted is enough to 'kill them'.

They are rarely seen, and just because they have been spotted doesn't mean they can be engaged in combat.

They are sacrificial beasts, and slaying one is just the destruction of a spirit entity's manifested shell, they can only truly be killed by very powerful magics and artifact level weapons.

The dungeon core creates and guides the Orthran to assist groups in the dungeon that have bitten off more than they can chew.

This is completely inaccurate. The Orthran are sent to fix mistakes, instances in the dungeon where there is an ongoing TPK that shouldn't have happened, or something went wrong in the planning. Its how the core fudges its rolls.

The Orthran are the personal pets of the dungeon core's harem.

The Hook

AKA, why does this matter and how is it possibly useful?

The Orthran are largely plot device creatures, something for the DM to drop into an encounter that has gone sour, to help bail out the party.

I know. YAWN.

The Orthran can also be used as a vector to deliver devilment, a new magic item, or something else. They are the messengers of the dungeon, so if the DM wants to drop a new item, try a new power up, or introduce a new sub-quest, these elusive and enigmatic critters can do the job. IOt can also be a litmus test for PCs, as the orthran are not dangerous or aggressive, but to gain their bonus, the creature must be slain.

Do they feel pain?

Is mortal death an ecstatic experience for an immortal orthran and are we the lesser for not being able to know communion with a greater power before being reincarnated deep in their home?