Path of Exile uses souls as one of its resources. Primarily, its main purpose is to charge or level-up items and skills used by players
Souls could be associated more often with the Vaal skill, which is granted by the corrupt Vaal skill gems.
Using the souls that can be collected may fuel the skill itself. It becomes more powerful and can deal more damage to your enemies.
Here are some ways to get souls in Path of Exile:
Get souls by killing enemies
The official Gamepedia page of Path of Exile suggests that the only way to get souls is to kill enemies.
One kill can grant you one soul. Although it would depend on the type of enemy you kill.
Killing a Rare enemy can give one soul. But killing the Unique ones can guarantee three souls.
Yet killing such enemies costs two percent of life lost alongside a one-second cooldown.
Some reminders about souls in Path of Exile
There are a few things you need to keep in mind about getting souls.
Each soul can charge one Vaal skill that is equipped on the character. But there is no chance of charging a secondary weapon set of a character.
Also, souls cannot be brought in different zone instances. But an instance's own soul counter could be maintained. A new instance would mean a new soul counter for each gem.
You must also be mindful of Soul Eater buff. Once you gained it, it will prevent you from collecting Vaal souls.