Per 
Item #: SCP-573
Object Class: Keter
Special Containment Procedures: [Scp-573 is to be contained in a 5m by 5m square concrete box 100 feet below underground the only contact that is to be made to Scp-573 is via electronic communication devices physical contact is to be made with Scp-573 ]
Description: [Scp-573 is a humanoid entity that is 1.6 meters in height with no sight of growing. It has an all-black appearance with no facial features. Its durability has been tested and nothing has even been able to hurt it taking an RPG to the face and not even showing signs of pain. Its strength and speed seem to be superhuman and it has shown the ability to outrun cars going at 40 miles per hour and lift a truck with ease.
Scp-573 is constantly pulsing the reason for this is unknown. It seems to have the ability to Phase in and out of two worlds as described by Scp-573 this gives it the ability to walk through any solid object and teleport. Whenever it attacks an entity usually provoked it seems to "charge up" when it does this it pulses more and more rapidly for approximately 10 seconds before attacking its victim 100% of all attacks have led in no survivors except for one which SCP-573 will always tell them the exact same words every time "I want a challenge"
Scp-573 intelligence is above most humans and has shown signs of knowing things it simply could not for example [DATA REDACTED] because of this SCP-573 is a threat to the entire foundation secrecy ]
In case of a containment breach, 5 d-class personnel must be gathered closest to the last known whereabouts of SCP-573
Addendum 573-B: Audio Log from Interview 573-1
Dr.███: Could you describe what happened, please
Major.██████: Yes, of course, what would you like to know
Dr.███: Describe how SCP-573 attacked
Major.██████: Well he was bloody fast, for one thing, he kept disappearing and reappearing in front of agents behind them
Dr.███: How badly did you hurt it
Major.██████: I don't think we did we emptied a few clips in but it didn't seem to affect it
Dr.███: So how did you escape
Major.██████: I didn't
Dr.███: excuse me
Major.███: I tried to escape once I saw my men being slaughtered like ants and I closed doors behind me too but before I knew it he had pinned me with his foot on my neck then he talked
Dr.███: Ah yes his voice how would you describe it and what did he say
Major.███: Demonic for one it sounded terrifying like it didn't belong in this world and it only said 4 words I want a challenge
Dr.███: Interesting well I believe we are done here Major pleasure seeing you
Major.███ is recorded leaving the room
Dr███: This is my formal request to begin termination testing on SCP-573
<End Log>
