This mod makes it so that the rare and unique skillbooks for various skills are sold by Skillbook Vendors.

Take the Walk in Shadows skillbook for example. Normally only 1 copy of this Level 1 skillbook exists within the game. With this mod, it is possible to buy the Walk in Shadows skillbook from any Scoundrel skillbook merchant, and it's possible to find it as a random drop when adventuring.

A full list of skillbooks made purchasable by this mod are the following-
FIRE SKILLS
Burning Blaze
Immolation
Lava Core

WATER SKILLS
Ice Wall
Mass Slow
Hail Attack

EARTH SKILLS
Boulder Dash
Petrifying Touch
Magical Poison Arrow
Summon Wolf
Earthquake

AIR SKILLS
Lightning Bolt
Make Invisible
Storm

WITCHCRAFT SKILLS
Create Undead Warrior
Finger of Death
Invulnerability

WARRIOR SKILLS
*Dust Devil
Whirlwind
Phoenix Dive
Terror

RANGER SKILLS
Barrage

ROGUE SKILLS
Walk in Shadows
Eye Gouge

*Dust Devil does not originally have a skillbook associated with it. This mod makes a new skill entry that is almost an exact copy of the original skill, and makes a Skillbook that allows it to be learnt.

INSTALLATION:
Place the files within the Zip into the corresponding folder locations within your Divinity - Original Sin installation folder.