Sinfiend

 (シンデモン Shindemon (= Sindemon) ) in the OCG, is an archetype originally created by LHK and used by the Jaakuna Clan in The Dragons Advent. It is an archetype of DARK Fiend monsters, often paying homage to Ars Goetia.

Play Style
The play style of the Sinfiends depends on the member of the Jaakuna clan who wields them. In general, the Sinfiends focus on a multitude of variants, using a multitude of Summoning mechanics. As seen with "Avaritia"'s variant, one can easily blend pieces of different variants to produce a mixture of a Sinfiend deck, with a less success than the success provided if using a specific deck revolving around 1 "Jaakuna" monster.
 * "Gula"'s variant focuses on quickly grabbing Materials and Fusion Summoning "Sinfiend of Gluttony", then Curse Summoning "Gula".
 * "Superbia"'s variant focuses on a harmonious balance between Level 3 and Level 4 monsters, which would end up in Evolute Summoning "Sinfiend of Pride" and then Curse Summoning "Superbia".
 * "Invidia"'s variant revolves around Level 4 monsters whose ATK is between 1000 and 2000 (exclusively from said bounds), in order to Bound Summon "Sinfiend of Envy" and then Curse Summoning "Invidia".
 * "Ira"'s variant revolves around Graveyard setup and Graveyard effects in order for the player to Composition Summon "Sinfiend of Wrath" and Curse Summoning "Ira" afterwards.
 * "Acedia"'s variant is diverse.
 * At first, it uses a variety of low-Level monsters which aid to Tribute Summon monsters, as shown by the sin it represents.
 * Later, it uses a variety of effects to quickly swarm Materials for "Sinfiend of Sloth" and then Curse Summoning "Acedia".
 * "Avaritia"'s variant revolves around Level 4 monsters (which can be aided by both "Ira"'s Base monsters being Level 4, "Superbia"'s Level 4s and most of "Invidia"'s Elements), with the purpose of Xyz Summoning "Sinfiend of Greed" and then Curse Summoning "Avaritia".
 * "Luxuria"'s variant revolves around Synchro Summoning using mostly Level 3 Tuners and Level 4 non-Tuner monsters (or vice-versa), in order for the player to Synchro Summon "Sinfiend of Lust" and afterwards Curse Summoning "Luxuria".

Weakness
The deck's main weakness is the limits of Extra Deck monsters in each variant, since they only have 2 of each (the "base" form and the "Jaakuna Sinfiend" form). However, the Spells and Traps of the deck provide universal support for every and any of the Jaakuna variants. Also, the "Virtue Prism" series, which are support for the "Rainbow-Eyes" and "Mirage Beast" archetypes, nullify almost any of the Jaakuna members from Summoning, making them a serious threat against them.