So this one took a bit. And I realized three things:
1) The writers of Dragon Ball Z (or the characters) equate immortality with invulnerability. Ah well.
2) Crazy Twilight is great fun. Hence, the superfluous addition to the last panel.
3) I couldn't remember how Nappa actually acted. Dragon Ball Z Abridged ( [link]
) had superseded all memory of the original.
EDIT: To answer "Who is Goku" - [link]