These potions use the permanent stat boost alchemy ingredients to boost an attribute by 5 points instead of the 2 you get from the ingredients alone. So save the ingredients!

Using a permanent stat boost potion will increase the amount of glory it costs to level that attribute, just the same as if you had raised it by spending glory. So it is worth saving them until you have spent as much glory on an attribute as you intend to spend.

The maximum for any attribute is 105 (100 plus the bonus from the legendary item). There are at least five or six of each permanent stat boosting ingredient. I found seven or eight for some attributes. So if you do a lot of exploring you might not need to raise an attribute to above 70 by spending glory to max it out.

Found on Taranis. Near to a chest next to a swamp golem. Part of a quest recieved from a hunter.

Found on Calador. In the western ruins (part of the main quest). In a room accessed via one of the 'puzzle ring' locks. Use astral vision to highlight the lock.

Bought on Taranis. From Nergal the mage in the basement of the main building in the mage camp.

Bought on Kila. From Tenya the voodoo priestess in the main village.

Found on Kila. Next to a chest on the island where you find Patty.

Bought on Antigua. From Emma the voodoo merchant in the harbour.

Bought on Kila. From Bahati. Find her near the small temple structure across a bridge from the main village.

Bought on Taranis. From Nergal the mage in the basement of the main building in the mage camp.