Subterror Behemoth Burrowing

You can banish 1 "Subterror" monster from your Graveyard; for the rest of this turn, face-down monsters you control cannot be destroyed by card effects, and your opponent cannot target them with card effects. If this card on the field is destroyed by a card effect: You can add 1 "Subterror" monster from your Deck to your hand. You can banish this card from your Graveyard, then target 1 "Subterror" monster you control; change it to face-down Defense Position.

Subterror Behemoth Dragossuary

Zombie/Flip/Effect

FLIP: You can activate this effect; this turn, "Subterror" cards you control cannot be destroyed by your opponent's card effects. You can only use this effect of "Subterror Behemoth Dragossuary" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Behemoth Phospheroglacier

Aqua/Flip/Effect

FLIP: You can send 1 card from your Deck to the Graveyard. You can only use this effect of "Subterror Behemoth Phospheroglacier" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Behemoth Speleogeist

Fiend/Flip/Effect

FLIP: You can target 1 monster on the field; change it to face-up Attack Position if it is in Defense Position, also change its ATK to 0. You can only use this effect of "Subterror Behemoth Speleogeist" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Behemoth Stalagmo

Rock/Flip/Effect

FLIP: You can discard 1 "Subterror" monster, and if you do, draw 2 cards. You can only use this effect of "Subterror Behemoth Stalagmo" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Behemoth Stygokraken

Sea Serpent/Flip/Effect

FLIP: You can target Set cards on the field, equal to the number of "Subterror Behemoth" monsters you control; destroy them. You can only use this effect of "Subterror Behemoth Stygokraken" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Behemoth Ultramafus

Pyro/Flip/Effect

FLIP: You can change all other face-up monsters on the field to face-down Defense Position. You can only use this effect of "Subterror Behemoth Ultramafus" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Behemoth Umastryx

Reptile/Flip/Effect

FLIP: You can target 1 monster your opponent controls; banish it. You can only use this effect of "Subterror Behemoth Umastryx" once per turn. When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Behemoth Voltelluric

Thunder/Flip/Effect

FLIP: You can target 1 Set monster your opponent controls; take control of it until your next End Phase. You can only use this effect of "Subterror Behemoth Voltelluric" once per turn.
When a face-up monster you control is flipped face-down, if you control no face-up monsters: You can Special Summon this card from your hand in Defense Position. Once per turn: You can change this card to face-down Defense Position.

Subterror Cave Clash

All "Subterror" monsters you control gain 500 ATK and DEF for each Set monster on the field. Once per turn, when a "Subterror" monster you control inflicts battle damage to your opponent: You can target 1 "Subterror" card in your Graveyard, except "Subterror Cave Clash"; add it to your hand.

Subterror Fiendess

Spellcaster/Effect

During either player's turn, when your opponent activates a card or effect: You can send this card from your hand or field to the Graveyard, then target 1 "Subterror" monster you control; negate the activation, then change the targeted monster to face-down Defense Position. You can target 1 face-up monster you control; change it to face-down Defense Position, and if you do, Special Summon 1 "Subterror" monster from your hand or Graveyard, in face-up or face-down Defense Position. You can only use each effect of "Subterror Fiendess" once per turn.

Subterror Final Battle

Activate 1 of these effects, also, after that, Set this card face-down instead of sending it to the Graveyard.
- Change 1 Set "Subterror" monster on the field to face-up Attack or Defense Position.
- Change 1 face-up "Subterror" monster on the field to face-down Defense Position.
- ATK and DEF of 1 "Subterror" monster on the field become equal to its combined original ATK and DEF until the end of this turn.
- This turn, activated effects of "Subterror" cards cannot be negated.

Subterror Guru

Dragon/Flip/Effect

FLIP: You can add 1 "Subterror" card from your Deck to your hand, except "Subterror Guru". You can target 1 other face-up monster on the field; change both it and this card to face-down Defense Position. This effect can be activated during either player's turn, if you control another "Subterror" card. You can only use each effect of "Subterror Guru" once per turn.

Subterror Nemesis Archer

Fairy/Effect

At the start of the Damage Step, if this card attacks an opponent's face-down Defense Position monster, and you control another "Subterror" monster: You can shuffle that opponent's monster into the Deck. If this card on the field is destroyed by battle or card effect and sent to the Graveyard: You can Special Summon 1 "Subterror" monster from your Deck in face-up or face-down Defense Position. You can only use each effect of "Subterror Nemesis Archer" once per turn.

Subterror Nemesis Defender

Beast-Warrior/Effect

During either player's turn, when your opponent activates a card or effect that targets exactly 1 Set monster you control (and no other cards), or when a Set monster you control is targeted for an attack by an opponent's monster: You can send this card from your hand or face-up from your field to the Graveyard, then target another monster you control that would be an appropriate target; that card/effect/attack now targets the new target. While you control a Set monster, this card cannot be destroyed by battle or card effects.

Subterror Nemesis Warrior

Warrior/Effect

During either player's turn: You can send 1 "Subterror" monster from your Deck to the Graveyard; Tribute this card and at least 1 other monster so the total original Levels Tributed equal or exceed the Level of that "Subterror" monster in the Graveyard, and if you do, Special Summon that monster in face-up or face-down Defense Position. If a "Subterror Behemoth" monster is flipped face-up while this card is in your Graveyard: You can Special Summon this card. You can only use each effect of "Subterror Nemesis Warrior" once per turn.

Subterror Succession

Activate 1 of these effects, also, after that, Set this card face-down instead of sending it to the GY.
• Send 1 monster from your hand or face-up field to the GY, and if you do, add 1 Flip monster with the same Attribute, but a different name, from your Deck to your hand.
• Send 1 Flip monster from your hand or face-up field to the GY, and if you do, add 1 monster with the same Attribute, but lower original Level, from your Deck to your hand.
You can only activate 1 "Subterror Succession" per turn.

Book of Eclipse

Change all face-up monsters on the field to face-down Defense Position. During the End Phase of this turn, flip as many face-down Defense Position monsters your opponent controls as possible face-up, then your opponent draws cards equal to the number of monsters flipped face-up by this effect.

Book of Lunar Eclipse

Discard 1 card, then target 2 face-up monsters on the field; change them to face-down Defense Position.

Book of Moon

Target 1 face-up monster on the field; change that target to face-down Defense Position.

Ash Blossom & Joyous Spring

Zombie/Tuner/Effect

When a card or effect is activated that includes any of these effects (Quick Effect): You can discard this card; negate that effect.
• Add a card from the Deck to the hand.
• Special Summon from the Deck.
• Send a card from the Deck to the GY.
You can only use this effect of "Ash Blossom & Joyous Spring" once per turn.

The Hidden City

When this card is activated: You can add 1 "Subterror" monster from your Deck to your hand. Once per turn: You can change 1 face-down Defense Position "Subterror" monster you control to face-up Attack or Defense Position. Once per turn, when an opponent's monster declares an attack: You can change 1 face-down Defense Position "Subterror" monster you control to face-up Attack or Defense Position, then you can negate the attack. You can only activate 1 "The Hidden City" per turn.

Subterror Behemoth Fiendess

Wyrm/Link/Effect

2 Flip monsters
Gains ATK equal to the combined original Levels of the "Subterror" monsters used for its Link Summon x 100. During your Main Phase: You can send 1 Flip monster from your Deck to the GY, and if you do, Special Summon 1 monster from your hand in face-down Defense Position to your zone this card points to. You can only use this effect of "Subterror Behemoth Fiendess" once per turn. Once per turn, if a monster this card points to is flipped face-up: Add 1 Flip monster from your Deck or GY to your hand.

Firewall Dragon

Cyberse/Link/Effect

2+ monsters
Once while face-up on the field (Quick Effect): You can target monsters on the field and/or GY up to the number of monsters co-linked to this card; return them to the hand. If a monster this card points to is destroyed by battle or sent to the GY: You can Special Summon 1 monster from your hand.

Firewall Dragon Darkfluid

Cyberse/Link/Effect

3+ Effect Monsters
If this card is Link Summoned: You can place counters on this card equal to the number of different types of Cyberse monsters in your GY (Ritual, Fusion, Synchro, Xyz). This card gains 2500 ATK for each counter on it during the Battle Phase only. When your opponent activates a monster effect (Quick Effect): You can remove 1 counter from this card; negate the activation, also, if this effect was activated between this card's attack declaration and the end of the Damage Step, this card can make another attack in a row.

Firewall eXceed Dragon

Cyberse/Xyz/Effect

2+ Level 4 monsters
This Xyz Summoned card gains 500 ATK x the total Link Rating of Link Monsters linked to this card. You can detach 2 materials from this card, then target 1 Link-4 Cyberse Link Monster in your GY; Special Summon it to your field so it points to this card, also you cannot Special Summon other monsters or attack directly for the rest of this turn.