Ability
Abyssal Tide. If you win the combat, you look at the rival's hand and they discard 2 cards you choose. Whoever defeats it is left with 0 DEF, and it is banished instead of going to the graveyard.
The myth
Jǫrmungandr, the Midgard Serpent, child of Loki and the giantess Angrboða, was cast by Óðinn into the ocean encircling the world, where it grew until it girdled all the earth and bit its own tail. It is the world's boundary made flesh: while it holds that circle, Midgard has shores. Twice it came within a breath of dying at Þórr's hands — once disguised as a grey cat in Útgarða-Loki's hall, once hooked on a line baited with an ox's head, when the god drove his feet through the boat to the sea floor hauling it up — and twice it escaped. At Ragnarök it will loose its tail at last, and the ocean will pour over the world. Þórr will kill it, then walk nine paces before falling dead of its venom: no one has ever beaten this creature without paying with their life.