From Warhammer 40k - Lexicanum
Mindshackle Scarabs are one of the Necrons' chief methods of controlling alien races. At the bearer's command, tiny scarabs bury into the victim's mind and bypass cerebral functions, turning the victim into little more than a puppet under the control of the scarabs' master.
- 1: Codex: Necrons (5th Edition), pg. 81