Introduction
Welcome to Duelyst! It’s me again. This thread is supposed to be a list of staples for different factions and decks. Intended to help out new players but here for everyone, hopefully this will give you a feel for which cards are almost always included in certain decks, and why.
I will not be detailing why each card is on this list, so if you have a question as to why a card is on this list, feel free to ask! Myself or other veterans of Doolist would be happy to help you.
Veterans! Please let us know what staples you think deserve to be included on this list, or even removed. I’m not experienced with every general and deck archetype in the game, so I may be incorrect in some of my assumptions 
Since rotations have been introduced to the game, I have elected to somewhat ignore them in this list. Rotated cards are marked with an asterisk.*
Let’s get started!
What is a staple card?
A staple card is a card that is used in nearly every deck of a certain type, simply because it is that good and that versatile.
For example, Makantor Warbeast (6 mana, 4/4 with Frenzy and Rush) is probably the biggest staple of all time in Magmar decks, as it allows you to get out of sticky situations, punish enemy positioning, remove threats indirectly or even push lethal. This versatility and strength of the card is why it is often an auto-include in any Magmar deck.
Factions:
Abyssian
Faction Staples: Sphere of Darkness*, Daemonic Lure, Desolator.
Maehv Staples: Prophet of the White Palm*, Gnasher*, Azure Horn Shaman. Desolator and healing are critical.
Swarm Staples: Furiosa, Crytpographer, Bloodtide Priestess, Deathfire Crescendo, Lilithe Blightchaser, Inkling Surge. Often Zyx, Soulshatter Grimwar, Soulshatter pact, Wraithling Swarm, Shadowdancer. Staples vary depending on the speed of the deck.
Creep Staples: Abyssal Crawler, Sphere of Darkness*, Painful Pluck, Munch, Yielding Depths, Ooz*, Abyssal Juggernaut, Obliterate*, Cassyva Soulreaper.
Mythron Staples: Darkfire Sacrifice, Ritual Banishing, Maehv Skinsolder, Consuming Rebirth, Sarlac, Underlord Xor’Xuul.
Arcanyst Staples: Prismatic Illusionist, Death Knell.
Dying Wish Staples: Lurking Fear*, Carrion Collector, Nekomata, Reaper of the Nine Moons.
The Neutral cards on this list are Prismatic Illusionist, Cryptographer, Azure Horn Shaman, Healing Mystic, Prophet of the White Palm*, Sarlac, Gnasher* and Zyx.
Magmar
Faction Staples: Makantor Warbeast, Lavaslasher, Natural Selection, Plasma Storm, Young Silithar, Earth Sphere, Ragebinder.
Faction Semi-Staples: Flash Reincarnation, Plasma Storm, Homeostatic Rebuke, Haruspex. Magmar has a ton of good cards, but sometimes you can’t fit all that goodness in one deck. Here’s those cards that you shed a single tear for as you cut from your deck.
Ragnora Staples: Greater Fortitude, often Egg Morph, Erratic Raptyr and Cryptographer, occasionally Wild Inceptor* or Morin-Khur*.
Competitive Starhorn Staples: Decimus, Tectonic Spikes. This is often combined with mech or just a ton of Magmar staples.
Mythron Staples: Hatefurnace, Krater, Greater Fortitude, Amplification, Diretide Frenzy, Bellow. Often Starhorn with BBS trigger minions such as Vindicator, Thraex, or Redsteel Minos, with Cryptographer for more triggers.
BBS Vaath Staples: Drogon, Cryptographer, Vaath’s Brutality.
Growmar Staples: Moloki Huntress*, Godhammer.
The neutrals on these lists are Decimus, Redsteel Minos and Cryptographer.
Makantor is quite possibly the biggest staple in game right now and ever.
Lyonar
Faction Staples: Azurite Lion, Silverguard Knight, Holy Immolation, Trinity Oath, Ironcliffe Guardian. Sunbloom is common, especially outside of Brome.
Argeon Staples: Windblade Adept.
Mythron Brome Staples: Zyx, Aurora, Jaxi, Jax Trusight, Grand Strategos.
Healyonar Staples: Ziran Sunforge, Scintilla, Sunforge Lancer, Sunriser, Azure Herald, Healing Mystic, Sunforge Cleric.
Titan Staples: Alabaster Titan (big surprise), Bloodtear Alchemist, Maw, Dancing Blades, Sworn Sister L’kian as draw engine. The wonderful thing about Titan decks is that they encourage creative deckbuilding, so staples are hard to pin down. Sojourner and Spelljammer are also good draw options. Opening Gambit removal minions such as these are very common, and necessary for a deck like this.
Bond Staples: Ironcliffe Guardian, Dioltas*, Divine Bond, Aegis Barrier. War Exorcist is common also.
The neutrals on this list are Saberspine Tiger, Sworn Sister L’kian, Spelljammer, Sojourner, Dancing Blades, Bloodtear Alchemist, Maw, Dioltas, Zyx, Azure Herald and Healing Mystic.
I pray to one day add Excelscious’ name to this list.
Holy Immolation is one of the biggest staples in game without a doubt. The Argeon list could be extended to include tempo, aggro etc. Tempest doesn’t make the cut due to alternatives in Skorn* and Sunbreaker, as well as swarm antisynergy.
Vetruvian
Faction Staples: Scion’s First Wish, Falcius*, Blood of Air.
Obelysk/Dervish Staples: Etheral Obelysk, Zirix Starstrider, Fireblaze Obelysk, Star’s Fury, Dunecaster, Accumulonimbus, Whisper of the Sands*, Allomancer*. Gust seems to be growing in popularity as well.
Notion of Starless Eternity: Neurolink, Silhouette Tracer, Iris Barrier, Staff of Y’kir, Wildfire Ankh, Scioness Sajj, Obdurator, Wind Striker, Aurora’s Tears.
Cyphiron Staples: Grapnel Paradigm, Psychic Conduit*.
Golem Vetruvian Staples: Celebrant, Dreamshaper, Golem Metallurgist, Sirocco, EMP. Boulder Breacher is very common as well, especially with Sajj.
Neutrals include Celebrant, EMP, Dreamshaper, Silhouette Tracer and Boulder Breacher.
A strong argument can be made for Kinematic Projection.
Vanar
Faction Staples: Chromatic Cold, Frigid Corona, Malicious Wisp, Hearth Sister (most often with Faie).
Kara Staples: Gravity Well, Luminous Charge, Grandmaster Embla. These can be cut if your list has a specific goal such as Arcanyst or Vespyr.
BBS Faie Staples: Bloodbound Mentor, Cryptographer, Cloud Caller. Alcuin Loremaster sees play here as well.
Vespyr Staples: Animus Plate, Crystal Cloaker, Snowchaser. These lists vary a lot. Personally I consider Crystal Arbiter to be Vespyr staple as well, and Wintertide when running Kara. It’s also common to see the Bonechill Barrier/Glacial Elemental combo, or even Icebreak Ambush (again, usually with Kara).
Cryptographer, Thunderhorn and Bloodbound Mentor are neutrals. Arguments can be made for Aspect of the Bear and Aspect of the Fox (although they are often used interchangeably).
Songhai
Faction Staples: Katara*, Mist Dragon Seal, Juxtaposition, Lantern Fox, Killing Edge, Gotatsu, Onyx Bear Seal, Mind-Cage Oni.
Mantra Staples: Phoenix Fire, Eight Gates, Firestorm Mantra, Shidai Stormblossom, Crescent Spear*, Rokadeptera, Abjudicator. The cheap spells listed in faction staples are critical. Ghost Lightning, Four Winds Magi and Chakri Avatar are staple for lists more focused on spells than Mantra.
Kaleos Staples: Scroll Bandit, Flamewreath, Grandmaster Zendo, Thunderhorn, EMP. Positioning spells listed above are critical.
Reva Staples: Crytpographer, Geomancer
Neutrals listed are Rokadeptera, Thunderhorn, EMP and Abjudicator.
I got pretty liberal here with what is considered a staple, as a lot of these cards are interchangeable and Songhai decks vary a lot from each other, for example using Phoenix Fire or Lantern Fox, but not both. Eternity Painter and Spelljammer deserve honorable mentions.
Miscellaneous Staples:
Neutral Minions
Turn One Staples: Bloodtear Alchemist, Healing Mystic, Primus Fist. While not a staple for every deck, definitely cards that every deck looks to when they’re trying to fill that opening turn slot.
Four Mana Staples: Thunderhorn and Sunsteel Defender* are strong neutral minions that can fill up the critical four mana spot in a deck that has need of that.
Card Draw Staples: Sojourner, Spelljammer. Blaze Hound is also quite good, although often only used in faster or cheaper decks, as it is otherwise outclassed. Sworn Sister L’kian is decent, but only in certain factions that have more good cards than bad ones (ie, Lyonar but not Vetruvian, etc).
Zoo Deck Staples: Zyx, Shiro Puppydragon, Replicant. These are cards often used in decks that try to swarm the opponent with minions.
Arcanyst Deck Staples: Owlbeast Sage, Blue Conjurer, Araras Prophet, Prismatic Illusionist. These are cards that benefit from spells, and can be used as a win condition. Trinity Wing and Manaforger can be great options as well.
Spell Reliant Staples: Abjudicator, Alcuin Loremaster. While not always used together or in Arcanyst decks, these are common in spell heavy decks, especially to reuse or ramp out a spell.
Dispell Staples: Ephemeral Shroud, Lightbender, EMP. While there are others, these are almost undoubtedly the strongest.
Healing Staples: Healing Mystic, Azure Herald, Rescue RX. The go-to for decks that need healing.
Memes
Serpenti is the only true meme staple, but be on the lookout for Prismatic Prism Barrier, especially when cast on a Prismatic Illusion created by a Prismatic Prismatic Illusionist.
Please leave your comments and questions below! This post will always be a work in progress, and be updated as the meta shifts. I consider this post a community effort, so please share your feedback to keep the list as accurate as possible.
If you’re wondering what a card does, Bagoum is a great resource. To find even more discussion on faction staples, look here or here, to the old staple post, here, or the even older one, here.
I updated the wiki!