A syntax question.
"One who rules without law, looks to his own advantage rather than that of his subjects, and uses extreme and cruel tactics against his own people as well as others." What are the elements of this sentence? Especially how does the "of" in "of his subjects" work? Thank you!

Question

Answer

It isn't actually a sentence. It is a noun phrase. It is describing someone who does three things:
One who = someone that:
(1) rules without law  = rules arbitrarily,
(2) looks to his own advantage rather that that of his subjects = does things that benefit him, rather than benefiting the people he rules
(3) uses (extreme and cruel tactics) against (his own people) [and] (others).

Answer

"that"= the advantage
So, "...looks to his own advantage rather than the advantage of his subjects...", that is "his subjects' advantage".