startneurotoxins
startneurotoxins is a console command available in 
Portal (series).
The command starts a neurotoxin countdown timer that synchronizes with any vgui_neurotoxin_countdown entities in the map and kills the player after the specified time. It is used in the final fight with GLaDOS in Portal.
Warning:Although still present, this command is non-functional in 
Portal 2. Instead, use a point_hurt to kill the player, and the countdown KeyValue of vgui_neurotoxin_countdown to set the timer.