Card Trivia:Yubel - The Ultimate Nightmare
- This is the cover card of Phantom Darkness.
- This is currently the only cover card of a Series 6 Core Booster in the OCG to not be Ghost Rare or Holographic Rare.
- This monster is an upgraded form of "Yubel - Terror Incarnate", and the ultimate evolved form of "Yubel".
- This card's Japanese name, "Yubel - Das Extremer Traurig Drachen", is German for "Yubel - The Extremely Sorrowful Dragon".
- This card's Japanese name contains the German neutral article "Das", referring to the androgynous nature of Yubel in the Yu-Gi-Oh! GX anime.
- This monster's name and appearance reference how Yubel transformed from a human into a dragon-like creature to become the guardian of The Supreme King.
- This monster, like its previous forms, has "eyes" and a "face" throughout different parts of its body, its knees have eyes, and its chest and twin dragon heads feature demonic faces.
- A total of sixteen eyes can be seen on this monster in its card artwork.
- The three "Yubel" monsters were released in the OCG/TCG in ascending rarities: "Yubel" was released as Super Rare, "Yubel - Terror Incarnate" as Ultra Rare, and this card as Secret Rare.
- In the Yu-Gi-Oh! GX anime, this card was the only "Yubel" monster whose attack animation consisted of this monster breathing fire from the two dragon heads; the two previous forms had the attacked monsters attack them instead. However, this was due to Jaden Yuki using a card to inflict damage to Yubel when this card attacked "Elemental HERO Neos".
- This card's Japanese name, "Yubel - Das Extremer Traurig Drachen", is German for "Yubel - The Extremely Sorrowful Dragon".
- This card is the first Level 12 monster in the OCG/TCG that is not a Fusion Monster.
- In the Shonen Jump magazine, a preview of this card, "Rainbow Dark Dragon", and "Dark Armed Dragon" had their Type listed as Beast, instead of their respective Types.
- One of this monster's dragon heads serves as the right arm of "Yubel - The Loving Defender Forever".
