I don't know what your copy of SoD says, but mine says this:
(italics mine)Necromantic Neuro-Link
Bipedal Assembly
Catalog 666-13B
Arcane Feedback Terminated
Power Supply:
Negative Energy Plane
16d12 Continuous Duty
Overload Followers:
12d8 Intermittent Duty
Class Sorcerer
I believe that 12d8 "intermittent duty" refers to Redcloak in some way, since it's his job to keep Xykon on full HP. Neither Harm nor any of the Inflict spells work like that though. Maybe it refers to Redcloak's hit dice at the time?