What is Negative Rarity?
Usually, players stack Increased Item Rarity to turn white items into Magic, Rare, or Unique items. We are doing the opposite.
By stacking Reduced Item Rarity, we strip the rarity off of items dropped by high-level monsters. This results in a massive amount of Normal items. Because we are farming high-level content, these aren't just trash white items. They are Item Level 82 Crafting Bases of top-tier base types, and exceptional items with extra sockets or quality.
The Thresholds
You can technically start with 0% rarity, but to see real results, you need to push into the negatives:
I recommend -60% Rarity as a starting point. This will allow you to see white items dropping from rare monsters, but to make them drop more consistently and in larger amounts, you should aim for -80% Rarity and eventually work your way up to -100% Rarity, which will allow for white items to consistently drop even from unique monsters. The lower into negatives you go, the better.
The Build & Gear
The only source of negative rarity in the game currently is 
Ventor's Gamble. By default, the lowest you can get is 25% reduced rarity and 6% increased rarity implicit, giving you 19% reduced rarity in total. You can also corrupt the ones that have 6% implicit for a chance at an increased range roll, going as low as 31% reduced item rarity for a total of 25% reduced item rarity.
To get the maximum benefit, you want to play as Ritualist which gets an additional ring slot from the 
Unfurled Finger ascendancy passive and a 25% multiplier for bonuses granted by rings and amulets from the 
Mystic Attunement ascendancy passive.
We combine that with the highest roll 
Ingenuity belt you can get and use a 
Kalandra's Touch to copy our best Ventor's Gamble ring.
Be careful with negative resistances on the Ventor's Gamble. While a small amount can be easily mitigated with the rest of your gear, the negatives get quickly multiplied into massive amounts, especially the ring copied by Kalandra's Touch and boosted by Ingenuity should not have a lot of negative resistances.
As for the build choice - you are essentially playing an unascended Huntress with no rings or belt. You need a build that functions well without relying on rings and belt for damage or survivability. Pick the strongest build you can.
For the 0.4 patch I chose the 
Blood Magic, 
Choir of the Storm 
Spark build. You can find my character profile here: LINK
Strategy 1: Farming Maps
Your goal is to drop Item Level 82 bases.
- Normal/Magic monsters drop items equal to Area Level.
- Rare monsters drop items +1 Level higher than Area.
- Unique monsters drop items +2 Levels higher than Area.
To get ilvl 82 bases from the highest number of monsters, we need to manipulate the Area Level and make sure that we are not adding any rarity to the map itself.
1. Atlas Setup
Make sure that your Atlas Passive Tree has Zero extra Item Rarity nodes. You do not want to counteract your Ventor's Gamble reduction in any way.
2. Waystones
Use Tier 16 Waystones with no Item Rarity modifiers. You can buy them from trade or craft them yourself by using Orbs of Alchemy and Exalted orbs until 6 modifiers. If a map has Increased Item Rarity, reroll it using an Omen of Chaotic Monsters or Omen of Chaotic Quantity. Corrupt the maps. You have a 12.5% chance for a T15 to upgrade to T16. Remaining maps can be sold, used to travel the atlas or used to farm Temple Crystals.
3. Atlas Nodes (+1 Area Level)
Travel to Corrupted Areas on your Atlas and look for the modifier: +1 to Monster Level of Area. This modifier can spawn on both Corrupted and Cleansed zones. Always check Cleansed maps after clearing the Nexus.
4. Tablets
Use the Visions of Paradise Unique Tablet to run the +1 Area Level node twice. On regular atlas nodes use regular Irradiation Tablets.
You can run any league mechanic you want, Breach and Abyss both work very well. I recommend running Abyss for the chance at Abyssal Depths which are always +1 Level higher than the map area level, so even the level 81 maps can lead to level 82 Abyssal Depths.
You want tablets with:
- NO RARITY
- effectiveness
- pack size
- increased monsters
- more abysses
- chance for abyssal depths
Strategy 2: Temple Farming
The Temple is currently the most lucrative method, but it requires a strict setup.
After hitting level 90, your temple will generate as an area level 81, which means that the rare monsters will drop items of item level 82 (exactly what we want). To farm them consistently you need at least -60% rarity.
While building the Negative Rarity Temple you can't use Alchemy labs, which increase the item rarity of the entire temple. This makes the temple much more restrictive, and prevents us from using a lot of rooms that every other temple uses. Here is my temple planner - LINK - you're free to use it as is, or make your own improvements. Be careful when following other people's temple ideas, because the planners have mistakes and unless someone actually made that temple in game, it might not be possible. Only follow reliable sources.
What to Loot & Sell
You are looking for specific items that crafters need for high-end gear.
1. Top Crafting Bases: Normal items at Item Level 80-82 depending on the base.
2. Skill Gems: Level 20 Skill Gems and Level 19-20 Spirit Gems.
3. Charms: High-level charms to craft with perfect Transmutations and Augmentations.
4. Skill Level 20 Staves and Wands (these go for multiple Divines, but you have to check for the levels manually).
5. Exceptional bases with additional sockets or overquality. The best ones are worth hundreds of Divines
The Drawbacks
This strategy is highly profitable but comes with "Quality of Life" issues you must be prepared for:
1. Inventory Management: Your inventory fills very quickly. You will spend a lot of time porting out to dump items.
2. Temple Backtracking - Path of Exile 2 currently does not have checkpoints in every Temple room. If you portal out to sell, you must run back from the start or your last checkpoint.
3. Merchant Tab Requirements: You need a lot of space (10+ Merchant Tabs recommended).
4. Ange Earnings Cap: The asynchronous trade system (Ange) has a currency limit. You will wake up to a full earnings tab and halted sales until you log in to clear it, if you're trading for thousands of currency items.
5. Notification Spam: You will sell items so fast that trade notifications may cover your screen, making it hard to interact with your inventory.
The Loot Filter (Mandatory)
You cannot run this strategy without a custom Loot Filter. I recommend going to poe2wiki.net and learning about the top item bases for every slot. Then go to poe.ninja/poe2/builds and look at the most popular rare items being used. Then price check them on the trade website, checking item levels 80, 81, 82 normal items that are not corrupted. If you want to understand why certain items need specific item levels, you can look up the available modifiers on these items on poe2db.tw/us/Modifiers. This is a lot of work, but once you learn which items are valued by other players, you will have a big advantage over players that didn't put that work in, and you will have access to untapped markets where you are one of the few people actually supplying the market with these items, which means a bigger share of the profits for you.
The economy and the meta changes frequently, so I can't list valuable items here, as they might not be valuable in a week.
Summary
Negative Rarity farming is a market-knowledge-heavy strategy. It requires a specific build, a willingness to manage inventory, and smart updates to your loot filter. However, if executed correctly, it provides a consistent supply of multi-Divine items and rivals the best currency strategies in the game. Just for some perspective, my current temple generates over 250 divines of profit per temple run. Good luck!
