This episode takes place on the eve of the World Duel Carnival (WDC) finals in Heartland City.
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
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. This episode takes place on the eve of
If you meant the 50th episode of the second series, the tone is much darker as the Barian Invasion reaches its peak. The One Standing Against the Three Emperors