Your alchemy skill will determine how long the effect of the invisibility potions will last. Alchemy shops randomly sell ingredients at varying levels of strength.
You can make invisibility potions with alchemy using a combination of:
• chaurus eggs – can be found in Falmer hives, and they are also dropped by Chaurus and Chaurus Reapers.
• nirnroot - they're usually found near water, or at Sarethi Farm between Riften and Ivarstead, where they are being cultivated.
• crimson nirnroot - a special type of Nirnroot found exclusively in Blackreach. It can be easily located if its chiming is followed. It’s so rare that you really shouldn’t use them for this.
• luna moth wing - only come out at night, and there is a lot of them around Talking Stone Camp, northeast of Rorikstead as well as inside Bloated Man's Grotto, north of Falkreath.
• vampire dust - can be found in dark lairs and caves all around Skyrim, and sometimes in the wilderness as well.
You can also buy up vampire dust and nirnroot in alchemy stores.
You can also use the Shadow Stone. Once a day, those under the sign of The Shadow can become invisible for an extended period. It is located south of Riften.
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