The Player Killer of Darkness is a cruel, brutal and cowardly man. He is paid by Pegasus to duel duelists of Duelist Kingdom and take all of their Star Chips if he wins. He usually hides in the dark and only duels or stalks at night. He wins through intimidation rather than skill, as he continuously threatens his opponents with flamethrowers.
The Player Killer of Darkness was undefeated in dueling, and easily defeated Mai Kujaku, taking all of her Star Chips. Yami Yugi challenged him to a duel to take Mai's Star Chips back. The Player Killer of Darkness agreed, as Pegasus promised him a generous amount of money for defeating Yugi Muto. He shackled Yugi in place and threatened him with flamethrowers, then used his Castle of Darkening to shroud his entire side of the field in darkness. But Yugi remained in control throughout most of the duel, calling the Player Killer of Darkness a coward for hiding in the dark. He dispelled the darkness with his Protective Seal Swords of Light, paralyzing the Player Killer's monsters for three turns, but the Player Killer of Darkness protected them with his Chaos Shield card. Soon, the Player Killer of Darkness was the one beginning to panic, and was quite agitated by Yugi's insults. He was defeated when Yugi launched his Gaia the Dragon Knight at the Castle to knock its flotation ring off and make it fall and crush the Player Killer's monsters (which never could have happened in the actual card game).
The Player Killer of Darkness was angry about being defeated by Yugi, and attempted to kill him with his flamethrowers, but his Millennium Puzzle protected him, and he used a Mind Crush to purify the Player Killer's evil heart.
In Season 4, Waking the Dragons, an apparition of the Player Killer of Darkness appeared as a lost soul in a circle while Yami was trying to find Yugi. It is debatable whether this was really the Player Killer's soul and not an illusion, however, as four other lost souls who appeared alongside him (Pandora the Conjurer, the Meikyu Brothers, and Bandit Keith), were neither dead nor trapped in Hell or taken by the Orichalcos. However, it is possible that the Meikyu Brothers were sent to Hell by Pegasus for failing him, and that Marik did the same to Keith and Pandora.
The Player Killer of Darkness' deck consist of Dark Attribute monsters. Almost all of his monsters contain unusual Attack and Defense stats, (As most monsters have attack and defenses that end with either a xx50 or xx00. But in the Player Killer's case most of his monsters have stats that end with xx10, xx80, xx30 Etc..). His signature monster is the Castle of Darkening, which envelopes his side of the field with a dark cloak, preventing his opponent from seeing his other monsters as well as giving his Dark Attribute Monsters a power boost. However, when the Player Killer is beginning to panic and is backed into a corner he plays several Magic Cards to increase his defenses to find a way to win the duel.
- It is possible that in addition to his soul going to Hell, his body was incinerated by his own flames, as the flames appear to be moving in his direction while he is shadowed during the Mind Crush. His box in the duel arena is never shown clearly afterward.