The best place to farm Empty Firewater Flask is Winterspring, where Winterfall Den Watcher (level 55-56) drops it at 10.0%. That is the vanilla 1.12 chance, not yet confirmed in Forever. 6 sources are ranked below by drop chance.
Best zones:

- Winterfall Den Watcher 67.5, 35.3
- Winterfall Shaman 66.1, 37.7
- Winterfall Pathfinder 42.1, 43.6
- Winterfall Totemic 30.3, 36.4
- Winterfall Ursa 66.1, 37.7
- Winterfall Runner 53.1, 34.7
All sources, by drop chance:
| Source | Level | Zone | Spawns | Side | How | Drop% | Map |
|---|---|---|---|---|---|---|---|
| Winterfall Den Watcher | 55-56 | Winterspring | 33 | Drop | 10.0% | map | |
| Winterfall Shaman | 56-57 | Winterspring | 21 | Drop | 10.0% | map | |
| Winterfall Pathfinder | 53-54 | Winterspring | 19 | Drop | 10.0% | map | |
| Winterfall Totemic | 54-55 | Winterspring | 18 | Drop | 10.0% | map | |
| Winterfall Ursa | 57-58 | Winterspring | 17 | Drop | 10.0% | map | |
| Winterfall Runner | 57 | Winterspring | 4 | Drop | 10.0% | map |
Needed for:
Quests:
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 (vanilla reference — from the 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.