Underworld
Yu-Gi-Oh! archetype · 4 cards
Ghost Charon, the Underworld BoatmanPGL2-EN005 · Premium Gold: Return of the Bling
Ghost Lancer, the Underworld SpearmanBLMR-EN023 · Battles of Legend: Monstrous Revenge
Ghost Sleeper, the Underworld PrincessBLMR-EN024 · Battles of Legend: Monstrous Revenge
Ghost Wyvern, the Underworld DragonBLMR-EN025 · Battles of Legend: Monstrous Revenge
Archetypes from YGOPRODeck and YAML Yugi (Yugipedia).