Per 
Special Containment Procedures:
SCP-4900 is to be contained within a reinforced, multi-layered containment chamber located at Site-27. The chamber must be constructed with a combination of high-density titanium alloy and reinforced concrete, with a minimum thickness of 5 meters. All entry points must be equipped with electromagnetic locking mechanisms and monitored by no fewer than four (4) on-site security personnel at all times. Surveillance of SCP-4900's containment chamber is to be maintained 24/7 via closed-circuit cameras.
Due to SCP-4900's ability to phase out of existence and exhibit extreme physical capabilities, any breach of containment must immediately trigger Site-27's lockdown protocol. Mobile Task Force Mu-13 ("Ghostbusters") is to be dispatched to re-contain SCP-4900 using non-lethal force and specialized containment equipment designed to counteract SCP-4900's abilities.
In the event of a containment breach, all personnel are to evacuate the vicinity of SCP-4900’s containment area. Under no circumstances are personnel to engage SCP-4900 directly. Communication with SCP-4900 is strictly prohibited unless authorized by Level 4 personnel or higher. Any attempts by SCP-4900 to communicate with other SCPs must be reported immediately to the Site Director.
Description:
SCP-4900 is an anomalous humanoid entity measuring approximately 200.6 cm (6'7") in height and weighing approximately 81.65 kg (180 lb). SCP-4900 is consistently attired in a black dress shirt with a red tie, a red coat, red slacks, and a red fedora. SCP-4900's face is entirely black and devoid of discernible facial features, with the exception of an extremely abnormal mouth. SCP-4900's teeth are maroon-colored, and its tongue and gums appear withered.
SCP-4900 exhibits the ability to phase out of existence at will, rendering it effectively intangible and allowing it to bypass physical barriers. Additionally, SCP-4900 possesses superhuman strength, capable of lifting in excess of 5,000 tons effortlessly. SCP-4900 has demonstrated the ability to reach speeds of up to Mach 27, making it one of the fastest entities contained by the Foundation.
SCP-4900 is highly violent and demonstrates a volatile temperament when interacting with Foundation personnel. SCP-4900 exhibits aggressive and agitated behavior during communication attempts, often resulting in physical altercations. SCP-4900 has a noted propensity for breaching containment and instigating chaos.
One notable incident involved SCP-4900 causing the detonation of the nuclear warhead at Site-27, resulting in the release of multiple high-risk and low-risk SCP entities, including but not limited to SCP-173, SCP-096, SCP-106, and SCP-049. SCP-4900 appears to possess the ability to communicate through any medium, including human languages, animal communication, and direct communication with other SCPs. This capability has earned SCP-4900 the moniker "The Man Upstairs" due to its apparent authority over other SCP entities.