Question

"All right," thought the Devil. "We will have a tussle. I'll give you land enough; and by means of that land I will get you into my power."

as a foil
as an antagonist
as a dynamic character
as the protagonist

Answer 1

The Devil in this example lays out a plan to take power over the protagonist. By this definition, the Devil is acting as an antagonist.

Answer 2

In this excerpt the Devil plays the role of the antagonist