- This card is based on the valkyrie Sigrun of Norse mythology, found prominently in the Poetic Edda. Betrothed to a man she deemed unworthy of her, Sigrun allies herself with the hero Helgi Hundingsbane, who destroys all supporters of the engagement. Helgi and Sigrun marry, but Helgi is betrayed and murdered by his own brother-in-law. Sigrun dies soon after of a broken heart, but is reborn again as the valkyrie Kara, and reunited with the reborn Helgi.
- Sigrun's story is similar to that of the more famous Brynhildr/Brunhilde, as both died after falling in love with a hero and being betrayed as a result of that love. Additionally, the card's name, "Sigurn," is close to the name Sigurd, the original Norse name of the hero Siegfried, who rescued Brunhilde.
- This is the only Valkyrie monster to be named directly after a figure from the original Norse attestations, and not from Wagner's compositions nor after a number (Brunhilde and Erda, used in Wagner's opera cycle, are Germanized forms of the original Nordic names Brynhildr and Jord, respectively.)
- Sigurn is also the only Valkyrie of the set whose mythic figure was decisively human (Sigrun's father was the human king Hogne). Traditionally, valkyries could originally have been recruited by Odin from any species, including human royalty.
- This is the first Valkyrie monster to be released in OCG before TCG.
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