Originally posted by TrueSkyl1n3
Having Oxygen cut off from around you, then trying to breath in and... nothing, slowly you'll just lose consciousness, struggling to inhale, and die.
Other than that... having a large drill-piece being inserted into your head whilst you're still awake, slowly entering through the Skull and down the Spinal cord, churning through the Bones and the Brain, eventually destroying your nervous system, in-turn killing you.
Although after you're dead then your Life Force (Spirit) will re-incarnate you as another being.
I passed out underwater once.
If you're panicked then it goes quicker than being slow and calm.
Less pain quicker knock out

.