Per 
Special Containment Procedures: SCP-8855 is to be contained in a standard humanoid containment cell at Site-██, with reinforced walls composed of a combination of lead and light-diffusing materials. The cell should be fitted with motion-detection sensors and infrared cameras to monitor the entity’s movements at all times. No less than two armed guards should be stationed outside the containment chamber at all times.
Personnel interacting with SCP-8855 must undergo a psychological evaluation prior to contact. Direct interaction with SCP-8855 is prohibited unless authorized by Level 4 personnel, and all communication is to be done remotely, via secure video feed. Any instances of SCP-8855’s anomalous abilities manifesting outside of its containment must be reported immediately.
SCP-8855 has been observed to utilize a unique pocket dimension, designated SCP-8855-A, which mirrors the real world but is fully corrupted into a shadowed wasteland. Unauthorized access to SCP-8855-A is prohibited under all circumstances. Any personnel who enter SCP-8855-A without proper clearance must be immediately retrieved and evaluated for exposure to potential cognitive hazards or dimensional trauma.
Description: SCP-8855 is a humanoid entity measuring approximately 2.1 meters in height with a gaunt, elongated frame. Its skin appears translucent under visible light, revealing dark, swirling patterns beneath the surface resembling ink suspended in water. SCP-8855's facial features are minimal, consisting only of faint indentations where the eyes and mouth would typically be located. Despite the lack of discernible sensory organs, SCP-8855 has demonstrated the ability to perceive its surroundings with exceptional precision.
8855 in it's containment cell.
SCP-8855 exhibits the anomalous ability to transition between our reality and SCP-8855-A, a pocket dimension accessible solely by the entity. SCP-8855-A resembles an inverted version of our reality, with all structures and terrain appearing as fragmented, shadowy ruins. The environment of SCP-8855-A is devoid of natural light, with visibility provided by faint, pulsing bioluminescent structures. Auditory distortions, such as distant whispers and disjointed echoes, are consistently reported by those exposed to the dimension.
Individuals who remain within SCP-8855-A for extended periods (typically exceeding 15 minutes) report symptoms of severe anxiety, paranoia, and, in extreme cases, auditory hallucinations suggesting hostile entities inhabiting the dimension. These claims remain unverified, as SCP-8855-A has shown resistance to standard remote surveillance methods.
Addendum 8855-1: Incident Log 8855-A
On ██/██/20██, SCP-8855 was observed entering an agitated state, pacing its containment cell and repeatedly striking the walls. Infrared cameras captured a significant energy spike emanating from SCP-8855, followed by a spontaneous rift leading to SCP-8855-A opening within the chamber. Despite containment protocols, two Level 2 researchers stationed nearby were inadvertently drawn into SCP-8855-A before the rift closed.
Recovery operations were initiated immediately. Mobile Task Force Omega-23 ("Shadow Sheperds") was deployed to locate and retrieve the researchers. Upon extraction, both individuals exhibited severe psychological distress, with one becoming catatonic. Preliminary debriefing revealed fragmented descriptions of humanoid figures observing them from the shadows, accompanied by persistent, dissonant laughter.
Following the incident, containment procedures were updated to include increased structural reinforcement and installation of dimensional stabilization devices within SCP-8855’s cell to mitigate further breaches.
Addendum 8855-2: Experiment Log
Experiment 8855-07
Objective: Determine the extent of SCP-8855's control over SCP-8855-A.
Procedure: A remote-controlled drone was equipped with high-resolution cameras and sent into SCP-8855-A during a controlled breach initiated by SCP-8855 under supervision.
Results: Upon entry, the drone’s video feed displayed an expansive, desolate landscape matching prior descriptions of SCP-8855-A. Approximately 300 meters from the entry point, the drone encountered an obelisk-like structure pulsating with an unknown energy signature. As the drone approached, the video feed was abruptly disrupted, and all attempts to retrieve it failed. Analysis of the final transmitted frames revealed SCP-8855 observing the drone from a distance, with its previously indistinct facial features now fully defined and resembling the visage of the drone’s operator.
Further experimentation with SCP-8855-A has been suspended pending O5 approval.
Addendum 8855-3: Audio Log
AUDIO LOG
DATE: ██/██/20██
NOTE: The following audio was recorded during an unauthorized breach of SCP-8855-A by Dr. ██████, who accessed the dimension without proper clearance. Dr. ██████'s status remains unknown.
[BEGIN LOG]
(Sounds of footsteps on brittle terrain, interspersed with faint, indiscernible whispers.)
Dr. ██████: "I… I think I see something. There’s a light… but it’s moving. Wait, no. It’s not a light. It’s—"
(Loud static, followed by a distorted voice overlapping Dr. ██████'s speech.)
Unknown Voice: "Why do you fear the shadows when the truth lies in the dark?"
Dr. ██████: "Who’s there? Show yourself!"
(A sharp, metallic screech is heard, followed by rapid, heavy breathing.)
Dr. ██████: "No. No, no, no. It's them. They're… everywhere."
(The recording ends with a deafening roar, followed by silence.)
[END LOG]
Conclusion: SCP-8855’s connection to SCP-8855-A represents a significant threat to both personnel and reality stability. Further breaches must be prevented at all costs, and exploration of SCP-8855-A is suspended indefinitely.