Katherine becomes a threat to Mystic Falls and Stefan and Damon decide to stop her at the Lockwood's masquerade ball. Bonnie, Jeremy, Alaric and Caroline help the Salvatore brothers but Katherine brings the witch Lucy (Natashia Williams) to protect her. Meanwhile Matt picks fight with Tyler, but Caroline hits Matt avoiding the fight; but the guest Aimee Bradley (Tiya Sircar) is also compelled by Katherine.
"Masquerade" is the episode where Katherine is finally defeated by Stefan and Damon. But the conclusion indicates that new characters will arrive at Mystic Falls. Who are they? My vote is seven.
Title (Brazil): "Masquerade"