There have been many threads calling out the short comings of the Great Vault (which shall be referenced as GV below) as well as comments defending it, both largely based on personal experiences. As anyone with experiences in statistics would know, personal experience is one of the worst form of proof of anything due to its nature of being biased. So instead of throwing out my personal experiences so far, I thought I would present some numbers done with simple math.
Let me clarify first that what I said below has nothing to do with whether an item from GV is an upgrade. There are many factors in there, such as how big of an upgrade (3 ilvl or 20 ilvl), currently gear, etc. that makes that calculation much more involved. Instead I am exploring the aspect of GV as bad luck protection (if you don’t think GV was presented as the new bad luck protection please read Raid vs Mythic+ loot tables - #5 by Kaivax).
Some constraints:
- All calculations are done based on Blood DK loot table. Other specs / class will vary.
- I assume the first two slots of the raid row share the same loot table.
- I assume the last slot of the raid row include drops from the last two bosses as well as the rest of the bosses.
- I assume all three slots from the M+ row share the same loot table from all possible drops from all dungeons.
- Since we are concerned about loot targeting, each item is treated as an unique item rather than each slot.
- PvP row is ignored. This is in my opinion the biggest disparity between PvP and PvE gearing thus far. The loot from PvP row is largely unnecessary. Yes if you get an upgrade it’ll speed up your gearing process, but if you don’t you’ll get there anyway eventually. Whereas if what you need from dungeon isn’t dropping then you are pretty much out of luck. But this is another topic entirely.
- I assume you full clear mythic CN and do all 10 x M+14.
- Rounding up to 2 decimal points because I am feeling generous.
Now, loot tables:
Shriekwing | 2
Huntsman Altimor | 3
Sun King’s Salvation | 4 | 1 weapon
Artificer Xy’mox | 2
Hungering Destroyer | 3
Lady Inerva Darkvein | 2
The Council of Blood | 3
Sludgefist | 2
Stone Legion Generals | 3
Sire Denathrius | 4 | 1 weapon
De Other Side | 10 | 1 weapon
Halls of Atonement | 7
Mis of Tirna Scithe | 6 | 1 weapon
Plaguefall | 7
Sanguine Depths | 8
Spires of Ascension | 7
The Necrotic Wake | 8 | 1 weapon
Theater of Pain | 10 | 1 weapon
Conclusions:
- If you are looking for a specific drop from one of the first 8 bosses in CN, the chance of getting the item is (2/21) + (1/28) = 14%
- If you are looking for a specific drop from the last 2 bosses in CN, the chance of getting the item is 1/28 = 4%
- If you are looking for a specific drop from a dungeon, the chance of getting the item is 3/63 = 5%
- If you are ok with certain item from first 8 bosses of CN or an item from dungeon, the chance of getting the item is 14% + 5% = 19%
Conclusion: GV does not work as bad luck protection.
Edit: As Hezzlocks-khazgoroth pointed out, the raid row could all draw from the same loot table as you clear, but this is most likely based on tier (first 8 bosses as one tier, last two bosses as another). I know for a fact that you can get drop from bosses you have not cleared up to Sludgefist. This means that if you don’t full clear the first two slots would contain drop table of first 8 bosses. If you full clear then all three slots will contain the entire drop table from the raid. If this is the case, assuming full clear, getting one item you want from the raid is 10% chance. Getting one item you want from raid or from dungeon would then be 15%.