Encryptid

Event: Encryptid is an event quest in the Fallout 76 add-on Wild Appalachia.

Quick walkthrough
The event summons an imposter sheepsquatch (a modified assaultron) and a constantly respawning horde of various other robots to defeat. It requires the party to activate pylons nearby to remove the shields that make the imposter sheepsquatch invulnerable before killing it to complete the event.

Detailed walkthrough
The event starts when a player character uses the terminal at the pylon ambush site. Starting the event requires an assaultron recall keycard to be in the player character's inventory, and can only be activated if the event has not occurred on the server for at least three hours. Starting the event spawns a three star legendary imposter sheepsquatch and a horde of other robots to attack any player character in the area. The robots include Mister Gutsies, protectrons and eyebot variants that move in swarms and explode on death, known as "Eyebombs".

The imposter sheepsquatch is invisible and invulnerable until the three pylons nearby are activated. Activating a pylon places a damaging effect on the player character who activated it and notifies all event participants of who has activated which pylon if they have the event tracked. The imposter sheepsquatch becomes visible and loses its invulnerability as long as all three pylons are all active. If any of the pylons become deactivated through the death of the player character who activated it, the imposter sheepsquatch becomes invisible and invulnerable again. The imposter sheepsquatch is very dangerous. It's head laser due to being a reprogrammed assaultron can easily tear through a player character's health if it is a direct hit, even in a full set of power armor, especially if it targets the ones who activated the pylons to regain its invisibility and invulnerability as long as one pylon is inactive.

The event ends once the imposter sheepsquatch is killed or time for the duration of the event expires before the primary objective is completed. Further robots will not spawn but those which are already present will remain active and hostile.