As you are exploring the woods around Freyers camp, you are going to eventually come across a set of two toxic plants that need to be frozen. You only have one Leviathan Axe, so how are you meant to freeze both plants to stop the toxic gas?
This is going to be a common part of the puzzles for the rest of the game, so take note of this one. You have recently unlocked the pink sigil arrows. When you throw the axe at one of these, it will cause the frost effect to last even when you recall the axe.
Shoot a sigil arrow at the toxic plant and throw the axe at it to freeze the plant. Recall the axe and throw it at the second plant. This will result in both of them becoming frozen and you will be able to make it past the area of toxic gas without any troubles.
If you are having some trouble with this, check out the video guide below.