Answer:
I am the greatest teacher out of them all, but alas in the end I kill my pupils.
Snake coiled round and round. Snake deep below the ground. Snake that's never had a head. Snake that binds but not with dread.
What is yellow, looks like the moon and has seeds?
Talks like this, a green wise man does. Guess my clue, you will.
What goes through a door but never goes in. And never comes out?
Special abilities and brightly colored underwear are all you need to be one of these.