Both Pako, Arcane Retriever and Haldan, Avid Arcanist are efficient threats that enable a strong card advantage engine from each player

Average Kess Deck View on Archidekt Commander (1) 1 Kess, Dissident MageKess, Dissident Mage Creatures (9) 1 Baral, Chief of ComplianceBaral, Chief of Compliance 1 Docent of PerfectionDocent of Perfection 1 Goblin ElectromancerGoblin Electromancer 1 GuttersnipeGuttersnipe 1 Jace, Vryn's ProdigyJace, Vryn's Prodigy 1 Laboratory ManiacLaboratory Maniac 1 Notion ThiefNotion Thief 1 Snapcaster MageSnapcaster Mage 1 Talrand, Sky SummonerTalrand, Sky Summoner Instants (22) 1 BrainstormBrainstorm 1 Cabal RitualCabal Ritual 1 Chaos WarpChaos Warp 1 CounterspellCounterspell 1 Cyclonic RiftCyclonic Rift 1 Dark RitualDark Ritual 1 Fact or FictionFact or Fiction 1 Force of WillForce of Will 1 Frantic SearchFrantic Search 1 Go for the ThroatGo for the Throat 1 ImpulseImpulse 1 Increasing VengeanceIncreasing Vengeance 1 IntuitionIntuition 1 Izzet CharmIzzet Charm 1 Lim-Dul's VaultLim-Dul's Vault 1 Mystical TutorMystical Tutor 1 NegateNegate 1 Rakdos CharmRakdos Charm 1 Reality ShiftReality Shift 1 Swan SongSwan Song 1 TerminateTerminate 1 Vampiric TutorVampiric Tutor Sorceries (18) 1 Blasphemous ActBlasphemous Act 1 DamnationDamnation 1 Dark PetitionDark Petition 1 Decree of PainDecree of Pain 1 Demonic TutorDemonic Tutor 1 DreadboreDreadbore 1 Faithless LootingFaithless Looting 1 GambleGamble 1 Gitaxian ProbeGitaxian Probe 1 Mind's DesireMind's Desire 1 Night's WhisperNight's Whisper 1 Past in FlamesPast in Flames 1 PonderPonder 1 PreordainPreordain 1 Serum VisionsSerum Visions 1 Toxic DelugeToxic Deluge 1 VandalblastVandalblast 1 WindfallWindfall Artifacts (10) 1 Aetherflux ReservoirAetherflux Reservoir 1 Commander's SphereCommander's Sphere 1 Dimir SignetDimir Signet 1 Fellwar StoneFellwar Stone 1 Izzet SignetIzzet Signet 1 Primal AmuletPrimal Amulet 1 Rakdos SignetRakdos Signet 1 Sol RingSol Ring 1 Talisman of DominanceTalisman of Dominance 1 Talisman of IndulgenceTalisman of Indulgence Enchantments (3) 1 Jace's SanctumJace's Sanctum 1 Mystic RemoraMystic Remora 1 Search for AzcantaSearch for Azcanta Planeswalkers (1) 1 Dack FaydenDack Fayden Lands (36) 1 Blood CryptBlood Crypt 1 Bloodstained MireBloodstained Mire 1 City of BrassCity of Brass 1 Command TowerCommand Tower 1 Crumbling NecropolisCrumbling Necropolis 1 Dragonskull SummitDragonskull Summit 1 Drowned CatacombDrowned Catacomb 1 Evolving WildsEvolving Wilds 1 Flooded StrandFlooded Strand 1 Mana ConfluenceMana Confluence 1 Polluted DeltaPolluted Delta 1 Reliquary TowerReliquary Tower 1 Scalding TarnScalding Tarn 1 Shivan ReefShivan Reef 1 Steam VentsSteam Vents 1 Sulfur FallsSulfur Falls 1 Sunken HollowSunken Hollow 1 Underground RiverUnderground River 1 Urborg, Tomb of YawgmothUrborg, Tomb of Yawgmoth 1 Watery GraveWatery Grave 8 IslandIsland 4 SwampSwamp 4 Mountain[/Lands]Mountain[/Lands] Ironically, it turns out that several of Kess's win conditions aren't spells, but creatures: Docent of PerfectionDocent of Perfection, Talrand, Sky SummonerTalrand, Sky Summoner, and GuttersnipeGuttersnipe all incrementally lead Kess to victory over the course of several turns, weaponizing each spell she casts

The Vault is the mechanic to deal with duplicates
While this is a steep increase, TCGplayer Direct sales have already reached $12.59, so its clear theres a good deal of demand