Spell of Mask is a Japanese set in the Yu-Gi-Oh! Official Card Game (OCG). It is the fifth Booster Pack in the OCG Series 2.
In other languages, the set Labyrinth of Nightmare is a combination of this set and the Japanese set Labyrinth of Nightmare.
The first portion of the set contains many cards from the beginning of Battle City, including cards from Yami Yugi's Duel with Marik Ishtar possessing Strings, Joey Wheeler's Duel with Mako Tsunami and Yami Yugi and Seto Kaiba's Duel with Umbra and Lumis. The next portion contains OCG original cards, including a number of FIRE-Attribute and Fairy-Type monsters, many of which inflict effect damage to the opponent or cause the player to gain Life Points. The set re-releases "Blue-Eyes White Dragon" as an Ultimate Rare.
Highly sought after cards include "United We Stand", "Mage Power", "Card of Safe Return" and "Torrential Tribute".
Each pack contained 5 cards and each box contained 30 packs.
There are 52 cards in total, or 56 in the Master Set. This consisted of: