Well, you can only have 18, but w the handy dandy copy/paste for your deck’s code, you can keep more on notepads and just switch them out. So I don’t know how everyone else plays the game, maybe you only run a few decks for competitive and maybe a few for fun, but I’ve made a TON of decks.
Right now I have 64 notepads saved in a folder for different decks I’ve made. My favorite part of this game is creating different decks centered around different themes and mechanics. They’re decent in competitive, but I never try to min-max or focus solely on efficiency. I focus on fun.
In case you’re curious, here’s a short list of my 64 decks:
Demon Hunter: Basic, Weapons/attacking support, and Soul fragments
Druid: Basic, C’thun, Jade golems, Baku, Ossirian tear quest, and Treants
Hunter: Basic, Secrets, Dragons, Beasts, Mechs, and No minions
Mage: Basic, C’thun, Dragons, Freeze, Highlander, Baku, Secrets, and No minions
Paladin: Basic, Mechs, Secrets, Kaleidosaur Quest/Librams, Reborn quest, Dragons, and Murlocs
Priest: Basic, Dragons, C’thun, Galakrond, Resurrect/Obelisk quest, Deathrattle quest, and Highlander
Rogue: Basic, Secrets, Stealth, Bazaar quest, Jade golems, Galakrond, Kingsbane
Shaman: Basic, Galakrond, Overload, Elementals/Heart of vir’naal quest, Jade golems, Greymane, Murlocs
Warlock: Basic, Demons, Archaeology quest, Discard quest, Lackeys, and Soul fragments
Warrior: Basic, Hack the system quest, Taunt quest, Pirates/weapons, Mechs, Damaged/Enrage, and Galakrond