Per 
Special Containment Procedures: SCP-XXXX is to be kept in a personally modified human containment chamber. Modifications made are one way exhaust vents as well as a two stage airlock for personnel to enter and exit. Personnel tasked with entering SCP-XXXX's chamber for study must be outfitted with decontamination suits, which must be kept airtight, and reusable respirators. In the event of SCP-XXXX becoming active with personnel inside the chamber, the airlocks will seal, the exhaust vents will purge the air, and the onsite security will sedate SCP-XXXX.
Update 01/01/01: MTF-Zeta-10-Arnoldii has been enlisted to accompany researchers when entering the chamber SCP-XXXX. Agent Arnoldii has proven to be a less invasive sedative than standard security tranquilizer rounds.
Update 02/02/02: MTF-Zeta-10-Arnoldii has been given clearance by head researcher Dr. Placeholder visit SCP-XXXX under camera supervision and upon leaving heavy decontamination. SCP-XXXX has shown a considerable change in attitude causing SCP-XXXX to be more amicable during study following the implementation of these visits.
Description: SCP-XXXX is the result of a captured agent, MTF-Zeta-10-Kerrii, forced into DNA splicing experiments. MTF-Zeta-10-Kerrii was an inactive sleeper agent on an assignment to infiltrate and relay information of the activities conducted at a lab located at [something], Mexico. Upon her activation and subsequent discovery by lab security personnel, MTF-Zeta-10-Kerrii was transformed into SCP-XXXX.
SCP-XXXX retains humanoid features of their previous form, but has obvious arachnid mutations including: Fangs,a partial carapace covering most of the torso and left side of the body, Urticating Bristles covering said carapace, Additional eyes (Posterior Lateral, Anterior Lateral, etc.) on the left side of the face, and an additional fully functioning human arm also on the left side of the body.
Upon further study, SCP-XXXX has demonstrated the ability to produce venom from their fangs and utilize their Urticating Bristles. The dispersed bristles are noted to cause eye and skin irritation as well as Pneumonitis. Should SCP-XXXX feel threatened, they have displayed the preference to use their bristles and flee rather than engage in serious conflict.
The following are video logs regarding the containment of SCP-XXXXAddendum XXXX-1:
