A Mountain of Mementos

TL;DR Recommendation: 1-3 Masks, Clear ALL Zones, pick up Black Empire Caches (especially in Lost areas).

Hi all. Did some testing recently, and I'll explain what I experienced. 672 Frost Mage, I went in through Visions of Orgrimmar with different clears and variations of Masks. Full Hourglass Tree, 12/12 upgrades. My route was Drag > Honor > Spirits > Wisdom. Didn't bother with Potions or the Odd Crystals (I kept forgetting about them); 5 Odd Crystals are worth about 160, so pick them up if you happen to see them, but I wouldn't go out of my way.

Summation:
There are two major decisions for how we can farm Visions:

Final Boss Only OR Clear All Areas
Thrall's Boss Chest increases in value the more Areas you clear. Alone, it's pretty piddling, 100 even on 8 Masks. Thrall gets stronger for each Area cleared, so the amount he's worth increases too. You also get all the Mob's drops, Boss Chests and their Caches that you pick up along the route. Despite how much longer it takes to clear the entire Vision, I'd say it's a lot more valuable than zerging Thrall over and over.

Few Masks OR Many Masks
Mobs, Caches, and Boss Chests will all drop more Mementos the more masks you wear. However, it's a lot easier and faster to clear the whole Vision with fewer masks. Let's look at both sides to see how they compare:

• 
  
• I timed a 2-Mask, Multitudes, Full Clear run worth 4605 Mementos at [16:19] minutes. This could definitely be done faster if you grouped up more packs and burned them down together. I cleared all the trash in my way, including buff rares, but didn't go off the route for every single pack. I picked up Caches (about 2 every Area) and ignored Potions and Odd Crystals.
• 
  
  
• Exact same route but at 8 Masks took me [38:03] minutes for a grand total of... 3971? That doesn't seem right. Did all the same packs (aside from a few extras for Gamon manipulation) and got at least 2 caches in each zone. From this, I surmise that there is a lot of variation in the number of Mementos dropped by mobs (perhaps thanks to Multitudes), a range of around 500-800 mementos difference (give or take an extra Cache) over the course of the run.
• 
  

Therefore, you'll still get a sizeable amount of mementos even from doing low-mask runs.

Taking both these into account, I would conclude that full clears at low mask counts to be the fastest and most lucrative way to farm Visions of N'zoth.

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Research:

The amount of Displaced Corrupted Mementos you find in Thrall's Boss Chest is increased by the number of areas you complete. Inside Thrall's Boss Chest at 5 Masks were:

• 
  
• Failure = 20
• 
  
• Thrall Only = 100
• 
  
• All 5 Areas = 500
• 
  

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The amount of Displaced Corrupted Mementos you find in the Lost (Rexxar, Gey'ara) areas' Boss Chest is exactly twice as much as the amount you get in the Corrupted (Zekhan, Garona) areas Boss Chest. A good thing to note is that you will still get the full chest amount even if you die and don't kill Thrall.

Area

1 Mask

2 Masks

5 Masks

6 Masks

8 Masks

Tainted

260

320

500

560

680

Corrupted

180

210

300

330

390

Lost

360

420

600

660

780

--

Black Empire Caches (purple chests) that you find in the Vision will give different amounts based on which Area you find them in. Masks will also increase the Cache's value, but honestly not by that much.

Area

1 Mask

5 Masks

8 Masks

Tainted

30-40

40-50

40-50

Corrupted

55-60

75-85

75-80

Lost

155-175

220-230

220-230

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Multitudes Mask ends up either having a large variance, or the variance is caused by other factors. Honestly, this will require more testing to figure out. If you are capable of clearing large amounts of enemies, go ahead and wear it. Just avoid wearing it with Vengeance.

Masks

Multitudes

No Multitudes

1

2064

2689

5

4526

-

6

4527

3597

8

3971

-

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I hope this helps. Use the above information to figure out what kind of farm is best for you. Happy farming!

Seeing as no one has shared how they grind mementos, i will just jump in and share what worked for me (might not be the most efficient method out there).

I just full cleared 1 mask orgrimmar over and over again, each run took around 10 min and granted 2k mementos. So it only took me a couple hours to finish the rest of the mementos i needed after doing all the other achievements and mounts.

Just to chip in what worked for me I did 6 masks in Orgrimmar.
The following masks were used:
- Burned Bridges
- Daredevil
- Dark Imagination
- Long Night
- Nemesis
- Vengeance
Average runs took around 11-11:30 mins which netted me 3,5k Mementos per run. I only focused on doing each zone as fast as possible. If I could skip some mobs I did )in Valley of Spirits you can hug the wall to skip last elemental and void mob by hugging the wall, in Valley of Honor you can skip elite bug next to AH by using sloped on the right side of the path etc) and only collected couple chests that were next to the route, didn't bother looking for them or going out of my way to collect one. As for class i was doing it on Ret paladin 684 IL.