The best place to farm Formula: Enchant Gloves - Advanced Herbalism is Swamp of Sorrows, where Swampwalker (level 38-39) drops it at 2.1%. That is the vanilla 1.12 chance, not yet confirmed in Forever. 5 sources are ranked below by drop chance.
Gold per kill: Swampwalker is worth about 5s 35c a kill in item drops (at Auction House prices). Gold farming spots, level 30-40
Best zones:

- Swampwalker 11.4, 38.8
- Molt Thorn 23.3, 49.2
- Swampwalker Elder 8.4, 34.4
- Tangled Horror 8.4, 34.4
- Mire Lord 5.5, 31.3
All sources, by drop chance:
| Source | Level | Zone | Spawns | Side | How | Drop% | Map |
|---|---|---|---|---|---|---|---|
| Swampwalker | 38-39 | Swamp of Sorrows | 11 | Drop | 2.1% | map | |
| Molt Thorn(rare) | 42 | Swamp of Sorrows | 1 | Drop | 1.9% | map | |
| Swampwalker Elder | 39-40 | Swamp of Sorrows | 8 | Drop | 1.8% | map | |
| Tangled Horror | 40-41 | Swamp of Sorrows | 28 | Drop | 1.8% | map | |
| Mire Lord | 42 | Swamp of Sorrows | 1 | Drop | 1.6% | map |
Drop% is the rate recorded in Forever once a source has been looted ten times; a greyed figure is the vanilla 1.12 chance from the world data (classic data: from the patch 1.12 world data, not yet confirmed in forever). Spawns counts the source's spawn points in the world data. "Side" names which side can kill the NPC when the other finds it friendly. The lead picks the best chance among sources that are not a rare spawn and have at least three spawn points.