Some ideas for episodes of Season 5 of MLP: Friendship is Magic (given in alphabetic order by episode title)
"Betrix't Hope and Despair" (two-parter, would be season-opener or season-ender): "While investigating rumors of King Sombra's resurrection, a task force lead by Prince Shining Armor of the Crystal Empire encounters a psychotic 'Great and Powerful' Trixie. Quickly captured and imprisoned by the Crystal Empire Prince, Trixie demands a 'duel to the death' with Princess Twilight Sparkle. Twilight reluctantly agrees to the demand, but on the hour of the duel an unexpected visitor arrives making an extraordinary claim about Trixie! Now Twilight must work with an old foe to get to the truth behind Trixie's psychosis and stop the renegade filly from hurting the innocent..."
"Bluest of Bluebloods": "Prince Blueblood visits Ponyville and the new castle there, but gets a cold shoulder from Rainbow Dash among others. To convince the haters of their wrong attitude, he and Rarity team up to