The Elder Scrolls V Skyrim – List of Craftable Alchemy Potions

Dwarven Oil and Taproot have the exact same effects: Weakness to Magic, Fortify Illusion, Regenerate Magic, and Restore Magicka.

If you create a potion from these ingredients, it would have all four effects (3 positive, 1 negative). With the Purity perk, the negative effect would not appear. As a potion, you can drink it.

If you create a poison from these ingredients, it would have all four effects (3 positive, 1 negative). With the Purity perk, the 3 positive effects would not appear. As a poison, you can put it on your weapon.

Woodcutter's Camp at Lake Geir, Altar in the Woods at Autumnshade, and there's a spot near Darklight Tower. Look for dead trees.