Trap Monster Trap Monsters are a type of Continuous Trap Card that is Special Summon ed as a Monster Card after activation , being treated as both a monster and a Trap Card simultaneously . In the manga , they are a separate type of Trap Card . Mechanics . Trap Monsters are Special Summoned to the field from the Spell & Trap Zone after they are activated , and are subsequently treated as both Monster Cards and Trap Cards . As such , they take up both a Monster Zone and a Spell & Trap Zone at the same time . If they are negate d with " Jinzo " or " Royal Decree " , they will return to the Spell & Trap Zone as Continuous Trap Cards with no effect , and will remain there even after " Jinzo " or " Royal Decree " are removed . If " Book of Moon " is used against an already active Trap Monster , the Trap Monster is set as a Trap Card again and can be activated and Special Summoned the next turn . If a card or effect that destroys monsters specifically ( like " Mirror Force " ) is activated , cards like " My Body as a Shield " can be activated to protect a Trap Monster , whereas cards like " Fake Trap " cannot be ; likewise , if a card or effect that destroys Trap cards specifically ( like " Heavy Storm " ) is activated , cards like " Fake Trap " can be activated , whereas cards like " My Body as a Shield " cannot . If a card or effect which can destroy both monsters and Traps ( like " Raigeki Break " ) is activated , both cards like " My Body as a Shield " and " Fake Trap " can be activated . In all cases , effects like that of " Imperial Custom " prevent Trap Monsters from being destroyed , even by battle . If a Trap Monster is treated as an Equip Card from the Monster Zone , such as due to the effect of " Relinquished " , it is treated only as an Equip Spell Card , not a Trap Card or Monster Card . Play style . Trap Monsters are typically used as an emergency defense to stonewall an opponent ( " Metal Reflect Slime " is particularly useful in this regard ) . They can also used to provide quick Tribute Fodder ( " Metal Reflect Slime " is great when combined with " Level Eater " ) , such as the Monarchs , and can in some cases be used offensively as well . Also , because they don ' t count as monsters while in a player ' s Deck or Graveyard , some effects might work on them as a Trap Card , while others ( like the effect of " Morphing Jar # 2 " ) don ' t see them as a monster . This can be helpful in some cases ( see All - Out Attacks OTK ) . Another use for Trap Monsters is for Synchro Summon ing or Xyz Summon ing . Since most Trap Monsters are Level 4 , they can be used to quickly Synchro Summon a Level 5 - 8 monster or Xyz Summon a Rank 4 monster . " Metal Reflect Slime " , which is too high a level to be useful for a Synchro Summon , can be used for Rank 10 Monsters such as " Superdreadnought Rail Cannon Gustav Max " . If combined with a Level 1 Tuner monster , they can be also used to Synchro Summon " Star Eater " . " Shape Sister " is a Level 2 Tuner Trap Monster that can be used to assist in Synchro Summoning . " Imperial Custom " makes Continuous Trap Cards indestructible . If you control a copy of " Imperial Custom " and a Trap Monster , the Trap Monster will not be able to be destroyed by battle or by a card effect . This combination is especially potent in defensive decks . Trap Monsters are also useful in a Uria Deck , as they provide the Deck with monsters that can also be used as a Tribute s to Summon " Uria , Lord of Searing Flames " as well as give him extra ATK points . It is usually a good idea to have " Trap Eater " and " Double Snare " and " Splendid Venus " in the Side Deck of a Deck using high concentrations of these cards , so that you can remove cards such as " Royal Decree " and " Jinzo " which obstruct the use of Trap Monsters . " Magic Planter " is also useful , allowing the player to send Trap Monsters to the Graveyard to draw cards ; this is particularly useful if the Trap Monsters have their effects negated , which causes them to remain on the field as Continuous Trap Cards only . " Judgment of Anubis " is useful to protect Trap Monsters from " Mystical Space Typhoon " .