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Is RNG Creep a threat to hearthstone? Over 20% of hearthstone cards now have random effects attached to them. We used to be under 8%.

Yes, Hearthstone is a card game, and any card game where you draw cards will inherently be somewhat RNG based. That's not what I want to talk about though. This post is in regards to cards that have random effects when played (Meaning any effects the player does not have full control over).
 
I took the time today to go through the basic+classic set, each of the expansions, and each of the adventures, and tallied up how many RNG effect cards exist in each set. I found that every single expansion and adventure thus far has increased the percentage of RNG based cards in the hearthstone card pool.
 
Before discussing it further here is what I found for each expansion/adventure in order of release.
 

Classic+Basic Set:

There are 372 cards total in the original Classic+Basic set of hearthstone cards, the base which this game has been built on. Of these 372 cards, 29 of them have an RNG based effect when played, meaning that 7.8% of the original cards are RNG based. The 29 cards are as follows:
 
Blood Imp
Deadly Shot
Forked Lightning
Mad Bomber
Sense Demons
Alarm-O-Bot
Demolisher
Doomgaurd
Knife Juggler
Master Swordsmith
Mind Control Tech
Misdirection
Stampeeding Kodo
Young priestess
Avenging wrath
Bane of Doom
Brawl
Mindgames
Tinkmaster Overspark
Ysera
Lightning Storm
Thoughsteal
Arcane Missiles
Multi-Shot
Succubus
Animal Companion
Cleave
Mind Vision
Soulfire
 

Curse of Naxxramas

Curse of Naxxramas adds only 30 collectible cards to the game, 7 of which (23.3% of the cards from this adventure) have RNG effects this brings our total to 36/402 of all Hearthstone cards (8.95%). RNG effect cards from Curse of Naxxramas are as follows:
 
Mad Scientist
Deathlord
Webspinner
Avenge
Dark Cultist
Anub'ar Ambusher
Voidcaller

Goblins vs Gnomes

The first hearthstone expansion, GvG, has 123 collectible cards. Of these 123 cards, 36 of them have RNG based effects when played. 29.3% of the cards in GvG are RNG based this brings our total of RNG based to 82/525, or 15.62%. The RNG based cards from GvG are as follows:
 
Clockwork Gnome
Ship's Cannon
Ogre Brute
Tinkertown Technician
Mechanical Yeti
Piloted Shredder
Gnomish Experimenter
Bomb Lobber
Madder Bomber
Recombobulator
Enhance-o Mechanico
Piloted Sky Golem
Blingtron 3000
Mogor the Ogre
Toshley
Dr. Boom
Sneed's Old Shredder
Mech-Bear-Cat
Glaivezoooka
Flamecannon
Unstabble Portal
Goblin Blastmage
Coghammer
Shadowboxer
Tinker's Sharpsword Oil
Ogre Ninja
Sabotage
Crackle
Powermace
Dunemaul Shaman
Ancestor's Call
Neptulon
Fel Cannon
Imp-losion
Ogre Warmaul
Bouncing blade
 

Blackrock Mountain

The Blackrock Mountain Adventure adds 31 cards. 5 of which have RNG effects attached to them (16.1% of cards from this adventure). This brings our total of RNG based cards to 87/556, or 15.65%. A very small increase from GvG, but an increase none the less. The RNG based cards from BRM are as follows:
 
Hungry Dragon
Nefarian
Flamewaker
Resurrect
Firegaurd Destroyer
 

The Grand Tournament

Unlike the GvG expansion who's theme was "Random Effects", the main theme of TGT was "Inspire". That being said, of the 132 collectible cards in the TGT expansion, 21 cards, 15.9% of the cards in the expansion, had random effects. This brings our total of RNG effect cards to 108/688. Further increasing to overall percentage of RNG based cards in Hearthstone to 15.69%. Again, only a small increase from the previous set, but still an increase. The RNG effect cards in TGT are as follows:
 
Flame Juggler
Mogor's Champion
Grand Crusader
Eydis Darkbane
Nexus-Champion Saraad
The Skeleton King
Mulch
Ram Wrangler
Lock and Load
Spellslinger
Effigy
Murloc Knight
Argent Lance
Tuskarr Jouster
Burgle
Tuskarr Totemic
Healing Wave
Elemental Destruction
Fist of Jaraxxus
Void Crusher
Dark Bargain
 

The League of Explorers

17/45 cards in LOE have random effects, that's 37.8% of this adventure. Bringing the card pool total to 125/733, or 17.1% of cards having random effects attached to them. The RNG effect cards from LOE are as follows:
 
Huge Toad
Jeweled Scarab
Tomb Spider
Gorillabot A-3
Anubisath Sentinel
Summoning Stone
Sir Finley Mrrgglton
Elise Starseeker
Raven Idol
Mounted Raptor
Dart Trap
Desert Camel
Ethereal Conjurer
Anyfin Can Happen
Museum Curator
Rumbling Elemental
Dark Peddler
 

Whispers of the Old Gods

Next comes Whispers of the Old Gods. Here we add an additional 26 RNG effect cards, our of 134 collectible cards in the expansion. 19.4% of the cards in this expansion have RNG effects. This brings our total to 151/867 cards having an RNG component to them (17.4% of all cards). The RNG effect cards of WotOG are as follows:
 
Zealous Initiate
Ancient Harbinger
Shifter Zerus
Nat the Darkfisher
C'Thun
Y'Shaarj, Rage Unbound
Yogg-Saron, Hope's End
Fiery Bat
Infest
Faceless Summoner
Demented Frostcaller
Servant of Yogg-Saron
Cabalist's Tomb
Selfless Hero
Ragnaros, Lightlord
Shifting Shade
Forbidden Shaping
Journey Below
Undercity Huckster
Xaril, Poisoned Mind
Evolve
Master of Evolution
Darkshire Librarian
Spreading Madness
Renounce Darkness
Malkorok
 

One Night in Karazhan

Like LOE, the Karazhan adventure brings with it 45 new cards, 17 of which (37.8%) have random effects attached to them. This brings our total up to 168/912 (18.4%) of all Hearthstone cards having random effects when played. The ONIK cards with random effects are as follows:
 
Netherspite Historian
Zoobot
Menagerie Magician
Barnes
Prince Malchezar
The Curator
Medivh (Atiesh technically)
Moonglade Portal
Firelands Portal
Babbling Book
Silvermoon Portal
Ivory Knight
Onyx Bishop
Swashburglar
Wicked Witchdoctor
Maelstrom Portal
Ironforge Portal
 

Mean Streets of Gadgetzan

MSOG was heavily centered around the discover mechanic, and while this does offer the player a choice at least, the 3 options they're given to choose from are still entirely random. MSOG brought in a total of 132 new collectible cards, 27 of which have RNG effects when played, meaning 20.5% of the cards in MSOG have RNG effects. Our total is now 195/1044 Hearthstone cards with RNG effects. 18.7% of all cards released to this point have RNG effects attached to them. The RNG based cards in MSOG are as follows:
 
Dirty Rat
Finja, The Flying Star
Madam Goya
Wrathion
Smuggler's Crate
Shaky Zipgunner
Hidden Cache
Trogg Beastrager
Greater Arcane Missiles
Grimscale Chum
Small-Time Recruits
Drakonid Operative
Shaku, the Collector
Devolve
Finders Keepers
Lotus Illusionist
Kabal Trafficker
I Know a Guy
Grimy Gadgeteer
Brass Knuckles
Grimestreet Smuggler
Grimestreet Informant
Don Han'Cho
Lotus Agents
Kabal Chemist
Kabal Courier
Kazakus
 

Journey to Un'Goro

Finally our latest expansions, Journey to Un'Goro, brings with it the Adapt mechanic. While there are generally fewer possible options with an Adapt than with a Discover, there are still more than 3, and thus there is a significant amount of RNG at play as to which adaptions you'll have to choose from. By my count Un'Goro brings us 44 cards with RNG effects, out of 135, for a total of 32.6% RNG based cards. Our final total of all cards released through expansions shows that 239/1179 all cards in current card sets are RNG based (20.3% of cards) .The RNG effect cards in Un'Goro are as follows:
 
Ravasaur Runt
Volatile Elemental
Primalfin Lookout
Pterrodax Hatchling
Thunder Lizard
Stonehill Defender
Vicious Fledgling
Servant of Kalimos
Volcanosaur
Gentle Megasaur
Tortollan Primalist
Elise the Trailblazer
Tortollan Forager
Elder Longneck
Verdant Longneck
Evolving Spores
Giant Anaconda
Jeweled Macaw
Crackling Razormaw
Tol'vir Warden
Stampede
Arcanologist
Primordial Glyph
Adaptation
Hydrologist
Lightfused Stegodon
Galvadon
Tortollan Shellraiser
Crystalline Oracle
Free From Amber
Shadow Visions
Curious Glimmerroot
Lyra the Sunshard
Hallucination
Mimic Pod
Volcano
Lakkari Felhound
Ravenous Pterrodax
Cruel Dinomancer
Chittering Tunneler
Ornery Direhorn
Molten blade
Explore Un'Goro
Sulfuras
 

Takeaways

It's not necessarily a bad thing that some cards have RNG based effects, but card games already have plenty of RNG to them based on card draw, and I believe there is a point where it becomes overkill. Every single hearthstone expansions has increased the total percentage of RNG based cards in the card pool without fail, and we are already at the point where over 20% of the cards in the game have random effects attached to them.

Release	% of RNG cards in release	Total % of RNG cards in HS
Classic+Basic	7.8%	7.8%
CON	23.3%	8.95%
GvG	29.3%	15.62%
BRM	16.1%	15.65%
TGT	15.9%	15.69%
LOE	37.8%	17.1%
WotOG	19.4%	17.4%
ONIK	37.8%	18.4%
MSOG	20.5%	18.7%
Un'Goro	32.6%	20.3%

  To be fair there are different magnitudes of randomness to hearthstone cards. Newer expansions have brought "randomness" in the form of the new discover and adapt mechanics, but I think most people would agree these mechanics are far less random than a Yogg tossing out 10 random spells on random targets.
 
That being said, there still comes a point where the game becomes much less about player skill, and much more about who get's lucky with their random card effects. I don't necessarily think we are at that point yet, but with the current trend it looks like we're getting closer and closer with every new card addition. Where do you draw the line on how much "randomness" is okay without the game becoming not at all competitive? I personally think the next few expansions really need to start to DECREASE the percentage of cards with random effects, rather than continuing to increase it, or we may soon see that tipping point where the competitive aspect of the game becomes a complete joke.
 

TL;DR:

Every single hearthstone adventure/expansion that has been released has increased the percentage of cards in the total hearthstone card pool that have random (not entirely controlled by the player) effects attached to them. The basic+classic set had random effects attached to 7.8% of cards, today over 20% of all hearthstone cards have a random effect attached to them. The game is arguably becoming more and more "luck" based every update.
 

Side Note

I'm sure I probably missed a card or two here or there, please let me know if you notice anything missing or any funny looking numbers (originally didn't include adventures but decided to later so I may have forgotten to update something).

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