first structure deck yugioh Yu-Gi-Oh! Legend of the Crystal Beasts Originally intended as a unique occurrence Structure Decks – Yu-Gi-Oh! TRADING

They mutate into the creature on top plus all abilities from under it.) Reach, trample Whenever this creature mutates, destroy target artifact or enchantment an opponent controls

R Rare Forbidden Forbidden Knightmare Mermaid X WATER Link 1 [ FiendLinkEffect ] ATK 1000 DEF - 1 "Knightmare" monster, except "Knightmare Mermaid" If this card is Link Summoned: You can discard 1 card

For this list, Im not considering cards that turn into dragons or double-faced cards/sagas

It was first sold to the public in 1999

(This card is NOT treated as a Spell Card when Summoned.) If this card was sent to the Graveyard after being excavated: Look at up to 3 cards from the bottom of your Deck, then place them on the top of the Deck in any order