cut connection of brain of from nervous system
Reading the Combine Advisor article on the Overwiki will help, as it explains just what the advisors due to humans -- the same thing the advisor did to Eli. To answer your question, however, the advisor, using its tongue-like probiscis, pierced Eli's cranium, thus incapacitating his central nervous system. Usually, this will kill a person instantly. For example, if you shoot a person in the head, what will happen? He'll die, of course! The same happened with Eli.
22.214.171.124 20:44, May 20, 2011 (UTC)