Confidence and the calm before the storm as the world's greatest duelists gather in one place.
If you meant the 50th episode of the second series, the tone is much darker as the Barian Invasion reaches its peak.
However, "Zexal Second" (or Zexal II ) typically refers to the second half of the series, starting from Episode 74. If you are looking for the 50th episode specifically within the Zexal II sequel (which would be Episode 123 of the overall series), that episode is titled (Japanese title: "Hero's Arrival! The One Standing Against the Three Emperors!"). Yu-Gi-Oh! ZEXAL — Episode 50: "Party Panic" Yu-Gi-Oh! Zexal Second Episode 50
In the original series numbering, of Yu-Gi-Oh! Zexal is titled "Party Panic" (Japanese title: "The Grand Feast of Justice! Calling on ESPer Robin!!").
A massive invitation-only party is held for the 23 finalists of the WDC. Yuma Tsukumo is excited to attend, but his friends—who aren't finalists—initially feel left out until Flip finds a way to sneak everyone in. Confidence and the calm before the storm as
The celebration is interrupted when a group of "duelists" led by a man named Nelson Andrews (who plays the character "ESPer Robin") causes a scene. Yuma eventually faces off against a mysterious challenger while the tension for the upcoming finals builds.
This episode marks the beginning of the final series of duels where Yuma's friends (like Anna, Nistro, and Nelson) sacrifice themselves to buy time against the overwhelming power of the Barians. If you are looking for the 50th episode
The Barian Emperors—Girag, Alito, Mizar, Dumon, Marin, and Nash—have launched a full-scale assault on Earth. Yuma is incapacitated after a psychological clash with Nash (Shark), leaving his friends to defend the city.