The stranger is a monster who sometimes appears when players have one or more Diamonds of Azzanadra in their inventory. He wields a poisoned dragon dagger and also has an unusual mechanic where he will follow the player closest to him. This may also happen while he is in combat with the target player.
He is non-attackable to the players not doing the quest Desert Treasure, and attempting to attack the stranger when not doing Desert Treasure will yield the message, "He has no interest in fighting you."
Most notably the stranger is capable of using the dragon dagger special attack MUCH MORE FREQUENTLY AND ENDLESSLY than a player can, and can even land two special attacks in successive ticks - players unable to use Protect from Melee or have low-level armour should avoid him at all costs. He does not seem to be limited to a special attack bar like a player is, and his attack speed varies throughout the fight.
The moment at which the stranger appears is random, as long as the player is carrying one or more of the diamonds. He can appear right after a diamond is obtained, which can be annoying since the player may be depleted of supplies. The more diamonds the player has, the greater the chance for him to appear.
When he appears, he says "You are not worthy holding that Diamond of Blood/Ice/Shadow/Smoke!"
If the player kills him, a chat window will pop up with them asking themselves "I wonder what that was all about?"