Ashes of the Damned, Astra Malorum, Totenreich, and Kowakujo had secret side quest easter eggs for Dempsey, Nikolai, Richtofen, and Takeo, and it seems that Rex Infernus lets everyone get involved with a unique secret! You can find a purple rift during spider rounds that unlocks a unique conversation between your Operator and Ava (The Entity), which provides further lore and additional loot after the conversation ends, with potential for Ray Guns and Perks!
To unlock the secret side quest, you must be playing as any of the 8 Dedicated Operators: Richtofen, Dempsey, Nikolai, Takeo, Maya, Weaver, Grey, or Carver. All you need to do is activate the Pack-a-Punch at the Nexus Forge and wait for a Deathspinner (spider round).
Once it's a Deathspinner Max Ammo round, look around each of the four temples at Caltheris's Sanctuary, Dravakar's Sanctuary, Nyxara's Sanctuary, and Veytharion's Sanctuary. Within one of these sanctuaries, you will find a purple rift on the wall that you can interact with. Upon doing so, you will be teleported into a room with the Entity.
The purple rift will appear in ONE of the Sancturies and only on these spider rounds, and it can be anywhere within the Sanctuary itself. After the cutscene, you will spawn outside of the rift with an abundance of loot, including Mystery Perks and potentially a Ray Gun!
There are 16 conversations you can have with the Entity, with each of the 8 characters having 2 quotes each for those of you who enjoy the lore:
Dravakar and the Entity warn Richtofen that he will become like the Warden if he does not mend his heart.
The Entity confirms that Richtofen was created from Samantha Maxis's memory.
Dempsey asks the Entity how old she is, but she forgets after several centuries of being trapped.
سەرچاوەی فەرمی بە زمانی ئینگلیزی: https://gamerant.com/black-ops-7-zombies-rex-infernus-secret-side-quest-guide/