Jedi-Bibliothek has uncovered the titles for the last four episodes of Star Wars Rebels! These will feature the darker episodes of the show. By the sounds of it, the final episode will be the showdown between Vader and Ahsoka. That episode, entitled “Twilight Of The Apprentice,” is an hour-long finale.  Check out the titles:

S2E18 “Shroud Of Darkness” March 2nd
SES19 “The Forgotten Droid” March 16th
S2E20 “The Mystery Of Chopper Base” March 23rd
S2E21 “Twilight Of The Apprentice” Part 1 March 30th
S2E22 “Twilight Of The Apprentice” Part 2 March 30th