DDランス・ソルジャー DD Lance Soldier [D/D Lance Soldier]
Level 2 DARK Fiend Tuner Effect Monster
ATK 400
DEF 400
You can only use the 1st and 2nd effect of this card’s name each once per turn.
(1) You can target 1 “D/D” monster you control; increase its Level by up to the number of “Dark Contract” cards you control and in your GY.
(2) If this card is in your GY: You can target 1 “Dark Contract” card you control; destroy it, and if you do, Special Summon this card, but banish it when it leaves the field.

DDディフェンス・ソルジャー DD Defense Soldier [D/D Defense Soldier]
Level 4 DARK Fiend Effect Monster
ATK 0
DEF 1800
You can only use the (1)st and (2)nd effect of this card’s name each once per turn.
(1) You can activate 1 of these effects;
● Target 1 “D/D” card in your Pendulum Zone; Special Summon it.
● Banish 1 “D/D” monster from your GY; if your “D/D/D” monster attacks this turn, your opponent cannot activate cards or effects until the end of the Damage Step.
(2) You can banish this card from your GY; add 1 “D/D” Pendulum Monster from your face-up Extra Deck or GY to your hand.

Note: The above two monsters reference LDS (Leo Duel School and Lancer Defense Soldiers)

DDD零死王ゼロ・マキナ DDD Reijioh Zero Machina [D/D/D Zero Demise King Zero Machinex]
Level 8 DARK Fiend Pendulum Effect Monster
ATK 3000
DEF 0
Pendulum Scale: 0
Pendulum Effect:
You can only use the Pendulum Effect of this card’s name once per turn.
(1) During your Main Phase, if this card was activated this turn: You can place 1 “Dark Contract” Continuous Spell/Trap from your Deck face-up on your field.
Monster Effect:
You can only use the (1)st and (2)nd monster effects of this card’s name each once per turn.
(1) If a face-up “D/D/D” and/or “Dark Contract” card(s) you control other than “D/D/D Zero Demise King Zero Machinex” is destroyed while this card is face-up in your Extra Deck (even during the Damage Step): You can Special Summon this card, then you can destroy 1 card on the field.
(2) If this card in the Monster Zone is destroyed: You can place it in your Pendulum Zone.

Note: Visually this card appears to be based on Himika, Reiji’s mother, as well as the suit of Hearts which she is associated with.

DDDD偉次元王アーク・クライシス DDDD Ijigen Oh Arc Crisis [D/D/D/D Great Dimension King Arc Crisis]
Level 12 DARK Fiend Fusion Pendulum Effect Monster
ATK 4000
DEF 4000
Pendulum Scale: 13
Pendulum Effect:
You can only use the Pendulum Effect of this card’s name once per turn.
(1) You can target any number of “Dark Contract” cards you control; destroy them, then you can Special Summon up to that many “Doom King” Pendulum Monsters from your Deck and/or Extra Deck.
Monster Effect:
Materials: 4 Fiend monsters (1 Fusion, 1 Synchro, 1 Xyz, 1 Pendulum)
Must be either Fusion Summoned, or Special Summoned (from your face-down Extra Deck) by banishing the above cards from your field and/or GY. You can only Special Summon “D/D/D/D Great Dimension King Arc Crisis” once per turn this way, no matter which method you use.
(1) If this card is Special Summoned: You can negate the effects of all face-up monsters your opponent currently controls.
(2) Can attack all opponent’s monsters once each.
(3) If this card in the Monster Zone is destroyed: You can place it in your Pendulum Zone.

Note: This card is meant to be based on Supreme King Z-ARC.

DDD創始王クロヴィス DDD Soushioh Clovis [D/D/D Founder King Clovis]
Level 6 DARK Fiend Synchro Effect Monster
ATK 2100
DEF 1900
Materials: 1 Tuner + 1+ non-Tuner monsters
You can only use the (1)st effect of this card’s name once per turn.
(1) If this card is Synchro Summoned: You can target 1 of your banished “D/D” monsters, or, if you control a “Dark Contract” card, you can target 1 in your GY instead; Special Summon it.
(2) If this card becomes banished: You can activate this effect; if your “D/D” monsters attacks a Defense Position monster this turn, inflict piercing battle damage.

Note: This monster is named after Clovis, the first king of the Franks and possibly the Clovis culture. As well as the suit of Clovers, associated with Reiji’s sibling, Reira through their C/C & C/C/C Deck.

DDD智慧王ソロモン DDD Chikeioh Solomon [D/D/D Wisdom King Solomon]
Rank 4 DARK Fiend Xyz Effect Monster
ATK 1000
DEF 2500
Materials: 2 Level 4 “D/D” monsters
You can only use the (1)st and (2)nd effect of this card’s name each once per turn.
(1) You can detach 1 material from this card; add 1 “D/D” card from your Deck to your hand.
(2) If this card becomes banished: You can target 1 “D/D” Effect Monster you control; that Effect Monster gains this effect until the end of this turn.
● If this card destroys a monster by battle: Inflict damage to your opponent equal to half that monster’s original ATK.

Note: This card is named after Solomon, the Israelite King who is said to have commanded an army of demons, in part, to construct the Temple in Jerusalem. Notably this seems to be referencing the suit of Spades most likely as well, though that is heavily associated with Reiji’s father, Leo Akaba.

DDD天空王ゼウス・ラグナロク DDD Tenkuuoh Zeus Ragnarok (D/D/D Sky King Zeus Ragnarok)
Link-3 DARK Fiend Link Effect Monster
ATK 2200
Links: Bottom-Left/Bottom/Bottom-Right
Materials: 2+ “D/D” Monsters
You can only use the (2)nd effect of this card’s name once per turn each.
(1) You can target 1 “D/D” or “Dark Contract” card you control; destroy it, also, during your Main Phase this turn, you can conduct 1 Pendulum Summon of a “D/D” monster(s) in addition to your Pendulum Summon. (You can only gain this effect once per turn.)
(2) When your opponent activates a monster effect in the hand (Quick Effect): You can banish 1 “D/D” monster and 1 “Dark Contract” card from your GY; negate the activation.

Note: This card is named after Zeus, the king of the gods in Greek mythos. As well as “Ragnarok”, the eschatology of the Nordic people.

零王の契約書 Reioh no Keiyakusho (Dark Contract with the Zero King)
Continuous Spell Card
This card is always treated as a “D/D” card. You can only use the (1)st effect of this card’s name once per turn.
(1) You can target 1 “D/D” card you control, except “Dark Contract with the Zero King”; you cannot Special Summon for the rest of this turn, except “D/D” monsters, also destroy that card, and if you do, Special Summon 1 “D/D” monster from your Deck.
(2) Once per turn, during your Standby Phase: Take 1000 damage.

異次元の契約書 Ijigen no Keiyakusho (Dark Contract with the Different Dimension)
Continuous Trap Card
You can only use the (1)st and (3)rd effect of this card’s name each once per turn.
(1) You can shuffle 2 “Dark Contract” cards from your GY into the Deck, then target 1 card your opponent controls or in their GY; banish it.
(2) Once per turn, during your Standby Phase: Take 1000 damage.
(3) If this card is destroyed: You can gain 500 LP, then, if it was destroyed by an opponent’s card effect, you gain 500 LP.

Source: YU-GI-OH!.jp