Blue Gate Keys are required to Duel him at the Gate.
He appears in-game after the player reaches Stage 6 of Duel World (5D's), at which point his Character Unlock Missions become available. Prior to February 18, 2021, he could only be unlocked through the special event Duelist Road: Clash at Crash Town.
When the Signers defeated the King of the Netherworld, Kalin was revived from the shadows. But remembering all the evil he caused as a Dark Signer, Kalin is caught in a cycle of guilt and regret. Wandering the world in search of answers, he settles in Crash Town—where he fights Duels with his very existence at stake.
When starting a Duel with Yusei Fudo, Kalin says "I did things to you that I regret... and can't take back."
When he wins the Duel, he says "Only you would think of Dueling to save me."
When he loses the Duel, he says "I'm glad you're the one who ended me, Yusei."
Crow Hogan
When starting a Duel with Crow Hogan, Kalin says "I did things to you that I regret... and can't take back."
When he loses the Duel, he says "Crow, I'm glad I was able to Duel you in my final battle."
Jack Atlas
When starting a Duel with Jack Atlas, Kalin says "I did things to you that I regret... and can't take back."
When he loses the Duel, he says "You don't seem satisfied with this victory, Jack."
Dark Signer Kalin Kessler
When starting a Duel with Dark Signer Kalin Kessler, Kalin says one of "To atone for my past, I must defeat the Dark Signers!", "No need to remind me of my sins. I've never forgotten them.", or "No matter how fast I run, I can't outrun my past!"
When he wins the Duel, he says "I will no longer run from my past.", followed by "I will fight for those who have lost their freedom!"
When he loses the Duel, he says "This is the price I must pay for my crimes."
Dark Signer Carly Carmine, Dark Signer Rex Goodwin
When starting a Duel with Dark Signer Carly Carmine or Dark Signer Rex Goodwin, Kalin says either "To atone for my past, I must defeat the Dark Signers!" or "No need to remind me of my sins. I've never forgotten them."
When he wins the Duel, he says "I will no longer run from my past.", followed by "I will fight for those who have lost their freedom!"
When he loses the Duel, he says "This is the price I must pay for my crimes."
Card-specific
Monsters
Before Kalin Synchro Summons "Infernity Doom Dragon", he announces "The sinister spirits that inhabit these creatures combine!", followed by "I Synchro Summon!" When Kalin Summons "Infernity Doom Dragon" (by any method), a cut-in frame of Kalin briefly appears, and he announces "I call forth Infernity Doom Dragon!" If its Summoning animation has not already played this Duel, a cutscene of "Infernity Doom Dragon" being Summoned plays afterwards.
Most of the time when Kalin attacks with that monster, he announces "Infernity Doom Dragon! Attack!" followed by "Infernal Flame Blast!"
When Kalin activates that monster's effect, he says "Infernity Doom Dragon's effect activates." followed by "Infernal Flame Breath!"
Before Kalin Synchro Summons "Void Ogre Dragon", he announces "Between the skies and the earth lies a chaotic void! I Synchro Summon!" When Kalin Summons "Void Ogre Dragon" (by any method), a cut-in frame of Kalin briefly appears, and he announces "Void Ogre Dragon!"
Most of the time when Kalin attacks with that monster, he announces "Attack, Void Ogre Dragon! Infernity Chaos Burst!"
When Kalin activates that monster's effect, he says "Void Ogre Dragon negates and destroys your card."
Before Kalin Synchro Summons "Trishula, Dragon of the Ice Barrier", he announces "Let the spear shatter the frozen wastes! I Synchro Summon!" When Kalin Summons "Trishula, Dragon of the Ice Barrier" (by any method), a cut-in frame of Kalin briefly appears, and he announces "Trishula, Dragon of the Ice Barrier!"
Most of the time when Kalin attacks with that monster, he announces "Trishula, Dragon of the Ice Barrier! Attack!"
When Kalin activates that monster's effect, he says "I banish a card from your hand, field, and Graveyard."
When Kalin Summons "Infernity Archer", a cut-in frame of Kalin's face briefly appears, and he announces "Appear, Infernity Archer."
Most of the time when Kalin attacks with that monster, he announces "Attack, Infernity Archer.", followed by "Infernity Crossbow!"
When Kalin Summons "Infernity Destroyer", a cut-in frame of Kalin's face briefly appears, and he announces "Appear, Infernity Destroyer."
Most of the time when Kalin attacks with that monster, he announces "Infernity Destroyer attacks."
When Kalin activates that monster's effect, he says "Since my hand's empty, my Destroyer deals 1600 damage."
When Kalin Summons "Infernity Doom Slinger", a cut-in frame of Kalin's face briefly appears, and he announces "Set your eyes on Infernity Doom Slinger!"
Most of the time when Kalin attacks with that monster, he announces "Infernity Doom Slinger attacks."
When Kalin activates that monster's effect, he says either "I banish Infernity Doom Slinger to negate the effect damage." followed by "Next, you choose whether to use Slinger's effect or not." the followed by "Which will you choose?", or "Infernity Doom Slinger's effect activates!"
When Kalin Summons "Infernity General", a cut-in frame of Kalin's face briefly appears, and he announces "Appear, Infernity General."
Most of the time when Kalin attacks with that monster, he announces "Infernity General attacks.", followed by "Infernity Blade!"
When Kalin activates that monster's effect, he says "When my hand's empty, I can use Infernity General's effect."
When Kalin Summons "Archfiend Soldier", he says "Here comes Archfiend Soldier."
Most of the time when Kalin attacks with that monster, he announces "Archfiend Soldier attacks."
When Kalin Summons "Gene-Warped Warwolf", he says "Come, Gene-Warped Warwolf."
Most of the time when Kalin attacks with that monster, he announces "Attack, Gene-Warped Warwolf."
When Kalin Summons "Infernity Archfiend", he says "Come out, Infernity Archfiend."
Most of the time when Kalin attacks with that monster, he announces "Attack, Infernity Archfiend.", followed by "Infernal Pressure!"
When Kalin activates that monster's first effect, he says "I can show you this card to Special Summon it."
When Kalin activates that monster's second effect, he says "Infernity Archfiend lets me add a card to my hand."
When Kalin Summons "Infernity Avenger", he says "The Tuner Monster, Infernity Avenger."
Most of the time when Kalin attacks with that monster, he announces "Infernity Avenger attacks."
When Kalin activates that monster's effect, he says "Infernity Avenger's effect activates from my Graveyard."
When Kalin Summons "Infernity Beast", he says "Let's go, Infernity Beast."
Most of the time when Kalin attacks with that monster, he announces "Attack, Infernity Beast.", followed by "Infernal Howling!"
When Kalin Summons "Infernity Beetle", he says "The Tuner Monster, Infernity Beetle."
Most of the time when Kalin attacks with that monster, he announces "Infernity Beetle attacks.", followed by "Beetle Blast!"
When Kalin activates that monster's effect, he says "Infernity Beetle's effect activates."
When Kalin Summons "Infernity Dwarf", he says "Go, Infernity Dwarf."
Most of the time when Kalin attacks with that monster, he announces "Infernity Dwarf attacks."
When Kalin Summons "Infernity Guardian", he says "Here's Infernity Guardian."
Most of the time when Kalin attacks with that monster, he announces "Attack, Infernity Guardian."
When Kalin Summons "Infernity Knight", he says "Come, Infernity Knight."
Most of the time when Kalin attacks with that monster, he announces "Attack, Infernity Knight."
When Kalin activates that monster's effect, he says "Infernity Knight's effect activates."
When Kalin Summons "Infernity Mirage", he says "Arrive, Infernity Mirage."
Most of the time when Kalin attacks with that monster, he announces "Attack, Infernity Mirage."
When Kalin activates that monster's effect, he says "I have no cards in my hand, so I can use my Mirage's effect."
When Kalin Summons "Infernity Necromancer", he says "Here comes Infernity Necromancer."
Most of the time when Kalin attacks with that monster, he announces "Infernity Necromancer attacks."
When Kalin activates that monster's Trigger Effect, he says "When my Necromancer is Summoned, it switches to defense."
When Kalin activates that monster's Ignition Effect, he says "My hand is empty, so I can activate Necromancer's effect."
When Kalin Summons "Infernity Patriarch", he says "Here's Infernity Patriarch."
Most of the time when Kalin attacks with that monster, he announces "Attack, Infernity Patriarch."
When Kalin Summons "Infernity Randomizer", he says "Let's go, Infernity Randomizer."
Most of the time when Kalin attacks with that monster, he announces "I'll attack with my Infernity Randomizer."
When Kalin activates that monster's effect, he says "Infernity Randomizer's effect activates."
When Kalin Summons "Vorse Raider", he says "Come on out, Vorse Raider."
Most of the time when Kalin attacks with that monster, he announces "Go, Vorse Raider."
Spells/Traps
When Kalin activates "Damage Gate", he says "I activate Damage Gate to revive a monster.", followed by "As long as its ATK are equal or less than the damage I took."
When Kalin activates "Full Salvo", he says "I flip over my Trap Card, Full Salvo.", followed by "I discard my entire hand, and you take 200 damage per card."
When Kalin activates "Infernity Barrier", he says "I activate my Counter Trap, Infernity Barrier."
When Kalin activates "Infernity Break", he says "I flip over my Trap Card, Infernity Break."
When Kalin activates "Infernity Force", he says "My Trap Card, Infernity Force.", followed by "I destroy the attacker and Special Summon an Infernity."
When Kalin activates "Infernity Inferno", he says "I activate my Trap Card, Infernity Inferno."
When Kalin activates "Infernity Launcher", he says "I activate the Continuous Spell, Infernity Launcher."
When Kalin activates that card's first effect, he says "Infernity Launcher's effect activates.", followed by "It sends an Infernity monster to the Graveyard."
When Kalin activates that card's second effect, he says "When my hand is empty, I can use my Launcher's extra effect."
When Kalin activates "Infernity Reflector", he says "I flip over my Trap Card, Infernity Reflector.", followed by "I Special Summon my destroyed monster and deal 1000 damage." [sic]
When Kalin activates "Into the Void", he says "I activate the Spell Card, Into the Void."
When Kalin activates "Phantom Hand", he says "I activate the Continuous Trap, Phantom Hand."
When Kalin activates that card's effect, he says "Phantom Hand's effect activates.", followed by "I banish my entire hand until my next Standby Phase."
When Kalin activates "Wave-Motion Inferno", he says "The Continuous Spell, Wave-Motion Inferno."
When Kalin activates that card's effect, he says "I send Wave-Motion Inferno to the Grave to use its effect.", followed by "It sends all the cards in my hand to the Graveyard."
When Kalin activates "ZERO-MAX", he says "I can activate ZERO-MAX when I have 0 cards in my hand.", followed by "All monsters with lower ATK than mine are burned to ash."