Brace yourselves. Today I received the first evidence of tiered drop rates within a rarity which stands up to scrutiny. (Some recent discussion on this topic can be found here.)
What I received was a list of 138 cards which are proposed as the set of cards which are less likely to drop than their rarity would suggest. The list came to me fourth-hand. The original source is unknown, but is reportedly someone who looked at the source code of the game. According to them, each card is assigned a hidden parameter of value 0, 1, or 2, and:
“if the value is 1, card drop rate will be halved comparing to drop rate of a cards with the same rarity
if it is 2 - the drop rate for this card will be 25% from normal drop rate for others cards with the same rarity”
The proposed list of cards and tier parameters is below. I’ve added the set and rarity to each card and sorted the list in a way that’s more useful (at least to me).
Tier Set Rarity Name
2 BFZ m Drowner of Hope
2 BFZ m Felidar Sovereign
2 BFZ m Hero of Goma Fada
2 BFZ m Nissa’s Renewal
2 BFZ m Omnath, Locus of Rage
2 BFZ m Serpentine Spike
2 BFZ m Ulamog, the Ceaseless Hunger
2 BFZ m Wasteland Strangler
2 BFZ r Akoum Hellkite
2 BFZ r Desolation Twin
2 BFZ r From Beyond
2 BFZ r Guardian of Tazeem
2 BFZ r Ruinous Path
2 BFZ r Titan’s Presence
2 BFZ r Veteran Warleader
1 BFZ m Akoum Firebird
1 BFZ m Bring to Light
1 BFZ m Drana, Liberator of Malakir
1 BFZ m Emeria Shepherd
1 BFZ m Exert Influence
1 BFZ m Greenwarden of Murasa
1 BFZ m Oblivion Sower
1 BFZ m Void Winnower
1 BFZ r Beastcaller Savant
1 BFZ r Blight Herder
1 BFZ r Brutal Expulsion
1 BFZ r Conduit of Ruin
1 BFZ r Defiant Bloodlord
1 BFZ r Endless One
1 BFZ r Gruesome Slaughter
1 BFZ r Lumbering Falls
1 BFZ r March from the Tomb
1 BFZ r Noyan Dar, Roil Shaper
1 BFZ r Radiant Flames
1 BFZ r Sanctum of Ugin
1 BFZ r Scatter to the Winds
1 BFZ r Shambling Vent
1 BFZ u Breaker of Armies
1 BFZ u Coastal Discovery
1 BFZ u Drana’s Emissary
1 BFZ u Grip of Desolation
1 BFZ u Grovetender Druids
1 BFZ u Kor Bladewhirl
1 BFZ u Malakir Familiar
1 BFZ u Ondu Rising
1 BFZ u Pathway Arrows
1 BFZ u Plated Crusher
1 BFZ u Processor Assault
1 BFZ u Resolute Blademaster
1 BFZ u Slab Hammer
1 BFZ u Tajuru Warcaller
1 BFZ u Ulamog’s Nullifier
1 BFZ u Ulamog’s Reclaimer
1 BFZ u Valakut Invoker
1 SOI m Angel of Deliverance
1 SOI m Engulf the Shore
1 SOI m Geier Reach Bandit / Vildin-Pack Alpha
1 SOI m The Gitrog Monster
1 SOI m Ulvenwald Hydra
1 SOI r Altered Ego
1 SOI r Anguished Unmaking
1 SOI r Cryptolith Rite
1 SOI r Drogskol Cavalry
1 SOI r Fevered Visions
1 SOI r From Under the Floorboards
1 SOI r Nephalia Moondrakes
1 SOI r Scourge Wolf
1 SOI u Aberrant Researcher /Perfected Form
1 SOI u Call the Bloodline
1 SOI u Daring Sleuth / Bearer of Overwhelming Truths
1 SOI u Gisa’s Bidding
1 SOI u Hope Against Hope
1 SOI u Howlpack Resurgence
1 SOI u Inner Struggle
1 SOI u Morkrut Necropod
1 SOI u Neglected Heirloom
1 SOI u Paranoid Parish-Blade
1 SOI u Silverstrike
1 SOI u Stensia Masquerade
1 SOI u Uninvited Geist / Unimpeded Trespasser
1 SOI u Veteran Cathar
1 SOI u Kessig Forgemaster / Flameheart Werewolf
1 KLD m Cataclysmic Gearhulk
1 KLD m Combustible Gearhulk
1 KLD m Noxious Gearhulk
1 KLD m Torrential Gearhulk
1 KLD m Verdurous Gearhulk
1 KLD r Aetherflux Reservoir
1 KLD r Authority of the Consuls
1 KLD r Bomat Courier
1 KLD r Eliminate the Competition
1 KLD r Fateful Showdown
1 KLD r Insidious Will
1 KLD r Wildest Dreams
1 KLD u Cloudblazer
1 KLD u Contraband Kingpin
1 KLD u Empyreal Voyager
1 KLD u Hazardous Conditions
1 KLD u Restoration Gearsmith
1 KLD u Unlicensed Disintegration
1 KLD u Veteran Motorist
1 KLD u Voltaic Brawler
1 KLD u Whirler Virtuoso
1 AKH m Bontu the Glorified
1 AKH m Hazoret the Fervent
1 AKH m Kefnet the Mindful
1 AKH m Oketra the True
1 AKH r Archfiend of Ifnir
1 AKH r Gideon’s Intervention
1 AKH r Honored Hydra
1 AKH r Trial of Knowledge
1 AKH r Trial of Solidarity
1 AKH r Trial of Strength
1 AKH r Trial of Zeal
1 AKH u Bontu’s Monument
1 AKH u Enigma Drake
1 AKH u Hazoret’s Monument
1 AKH u Kefnet’s Monument
1 AKH u Lord of the Accursed
1 AKH u Oketra’s Monument
1 AKH u Rhonas’s Monument
1 AKH u Trial of Ambition
1 AKH u Wayward Servant
1 HOU m Angel of Condemnation
1 HOU m Wildfire Eternal
1 HOU r Doomfall
1 HOU r Imaginary Threats
1 HOU r Inferno Jet
1 HOU r Overcome
1 HOU u Appeal → Authority
1 HOU u Bloodwater Entity
1 HOU u Claim → Fame
1 HOU u Consign → Oblivion
1 HOU u Farm → Market
1 HOU u Resolute Survivors
1 HOU u River Hoopoe
1 HOU u Struggle → Survive
1 HOU u Unraveling Mummy
Unfortunately, this proposed list was shown to me after booster crafting destroyed the easiest ways to test it (via dupe data). But it’s still testable by other means. In the “bulk open” tabs of the drop rates spreadsheet, individual card drops have been recorded for various sets. For example, the cards opened for 387 KLD rare drops (out of 58 possible KLD rares) have been recorded. The proposed list says 7 of those 58 cards are “tier 1”, and drop less often than the rest. So what do the stats say?
Assuming uniform drop rates, it’s common sense that we can choose any group of 7 KLD rares, and the chance of a KLD rare dropping as one of those 7 will be on average 7/58 (12.1%). On top of that, given 387 drops, we can pick a confidence level we’d like to have (say 99.9%), and do some stats to get a confidence range around that average (such as 6.6% to 17.6%). Another way to put it: If we run the experiment 1000 times, each time recording 387 rare drops, we can expect our chosen group of 7 KLD rares to get between 6.6% and 17.6% of the drops in 999 of those experiments (and probably only just outside that range in the 1000th run).
On the KLD bulk open tab, 15 out of 387 rare drops (3.9%) belong to the group of 7 in the proposed list. 3.9% is outside of our 99.9% confidence range (6.6% to 17.6%)! So, assuming the proposed list is independent of the data, we can say with 99.9% confidence that the 7 KLD rares in the proposed list do indeed drop with lower chance than the rest of the KLD rares. For other sets and rarities the trends look like they go in the right direction, but in most cases there isn’t enough data to prove anything statistically. Also note that we haven’t proven the theory that the chance is “halved”, just shown that the chance is lower.
“Assuming the list is independent of the data” is important - someone could look at a dataset of 387 recorded drops, pick the least-dropped 7 cards, and claim they are less likely to drop than the rest. In that case, the analysis would be invalid, since we’d effectively be trying to use some data to prove itself. The presence of two non-mtgpq cards in the list (“The Gitrog Monster” and “Gisa’s Bidding”) makes a genuine source more plausible to me, but the source of the list is still an open question.