They already have Scarr btw
SR13-JP002 Ankokukai no Monban Genta (Genta, Gatekeeper of Dark World) / Genta, Gateman of Dark World
DARK Fiend / Effect
You can only Special Summon “Genta, Gatekeeper of Dark World(s)” once per turn.
(1) You can discard this card to the GY; add 1 “The Gates of Dark World” from your Deck to your hand.
(2) If this card becomes banished and you control a “Dark World” card: You can Special Summon this card.
SR13-JP003 Ankokukai no Insha Perl / Perl, Hermit of Dark World
DARK Fiend / Effect
You can only use the effect of this card’s name once per turn.
(1) If this card is discarded to the GY by a card effect: You can target 1 “Dark World” monster in your GY, except “Perl, Hermit of Dark World”; Special Summon it to either field, then, if this card was discarded by an opponent’s card effect, you can Special Summon 1 of your Fiend monsters that is banished, in your hand, or in your GY to either field.
SR13-JP026 Ankokukai no Fumidono / Dark World Library
Continuous Spell Card
You can only use the 1st and 2nd effect of this card’s name each once per turn.
(1) During your Main Phase: You can discard 1 “Dark World” monster, and if you do, all “Dark World” monsters you currently control gain ATK equal to the discarded monster’s Level x 100 until the end of this turn.
(2) If your monster(s) whose original Type is Fiend is discarded by the effect of a “Dark World” card or an opponent’s card (even during the Damage Step): You can discard 1 card, then draw 2 cards.
SR13-JP005 Lucent, Netherlord of Dark World (Reprint)
SR13-JP006 Latinum, Exarch of Dark World (Reprint)
SR13-JP015 Ceruli, Guru of Dark World (Reprint)
SR13-JP022 Fabled Raven (Reprint)
SR13-JP028 Charge Into a Dark World (Reprint)
SR13-JP032 Card Destruction (Reprint)
SR13-JP036 Dark World Smog (Reprint
SR13-JP037 Mind Crush (Reprint)
SR13-JPP04 Snoww, Unlight of Dark World (Reprint)
SR13-JPP05 The Gates of Dark World (Reprint)