Toxin Code Name: “TYRANT”
Type: Nanite NeuroToxin, Self Replicating
Effects: Targets the Five Senses to create a painful sensory overload that ends in death.
Beta Stage Results: Explosion of the Head, taken out for final testing.
Final Stage Results: Instantaneous Death

In Depth Explanation: After injection, the Nanites immediately target the nervous system, latching onto the Axons of nerve cells and drilling into them. After that, they anchor themselves to the nerves, and start leaking in a dormant version of TYRANT toxin in throughout the nervous system, afflicting the entire body within a matter of seconds. After that, it is at the controllers discretion when and where to activate the Toxin.
If and when the toxin is activated, it sends the nervous system into overdrive, initially creating great shock and pain, distorting the subjects ability to perceive reality, making everything they look at, feel, taste, smell and sound demonic and horrifying, so the last emotion the person ever feels is fear, before the brain shuts down from the inability to process the over load of the senses, ending, of course, in death.
In the case that the nanites should be removed, a small chip, about a half a nanometer in size, will anchor into the inside of the axon, continuing to transmit the signal of the toxin and will produce new nanite bodies, that will grow and re-latch onto the axons again.
In the case that fails, the toxin, already spread throughout the system, is activated, instantaneously killing the subject.