Brimstone

To unlock the ability to collect Brimstone, you need to complete its Research at the Gorthank Institute. There are two researches related to Brimstone. The “Brimstone Research” is the basic one and it will give you the Brimstone tutorial.

To farm Brimstone, you have two options.

From Brimstone Fumes

1. Go to the Brimstone Springs at the Smoking Lands, located to the east of Tariv, in northern Demeniss.
2. Use Healing Force Palm on the vents to close them up one by one. It can be tricky as you need to properly target the vents. Point the blue reticle to the white dot. When a vent is healed, it will glow in green. And it will stop smoking, of course.
3. Activate Nature’s Snare and point it at the last vent. Wait a few seconds for the gas to concentrate.
4. When you see the golden sphere forming at the top of the vent, cancel Nature’s Snare.
5. Collect the newly formed Brimstone. The bundle may spill and fall, so keep an eye on it as it flies out of the vent in the end. Continue clicking on “Collect” until you pick up all items.

From Brimstone Lake Crabs

You can find stone crabs around the shores of the Brimstone-poisoned water at Brimstone Lake Watchtower. This location is just to the east from the Smoking Lands, in northern Demeniss. Note that the area might be hostile, depending on your game settings and current progress.

You will notice them from afar by the geysers. They often spit water high up in the air while dormant. These stone crabs are very easy to defeat and they drop Brimstone.