Can you create spell-scars from spells prepared with knowledge pool?

Question

I'm playing a magus, and I'm considering taking the spell-scar arcana, but I'm not entirely sure how it functions.

Is it possible to prepare a spell through Knowledge pool and then create a spell-scar from that spell?

Knowledge pool descrition:

...the magus can treat any one spell from the magus spell list as if it were in his spellbook and can prepare that spell as normal that day...

Spell-scar Arcana description:

functions like scribe scroll feat.

Scribe scroll description:

You can create a scroll from any spell you know.

Answer 1

The only spells a magus or wizard “knows” are those in his spellbook. The knowledge pool says that you count those spells as being in your spellbook—thus you “know” those spells as well as any magus or wizard ever knows any spell (well, barring an archetype to change either into spontaneously spellcasting; I know magus has at least one of those).

So yes, you can scribe scrolls, or make spell scars, of those spells from the knowledge pool. This is pretty useful, but you should be aware that scrolls are very expensive, and spell scars are further limited to at most 18 spell levels’ worth, so there is a distinct limit on how good this option actually is. Personally, I’d call it good enough to take if you want it, but not so good that I would recommend it even to someone who wasn’t specifically interested in it.

Jason Bulmahn, Paizo’s lead designer, does suggest that this seemed like an oversight to him. However, as no errata has been issued, I surmise that it was either not important enough to bother correcting, or others at Paizo convinced him that it was not an oversight and was intended. Certainly, this ability, while relatively minor, goes a long way towards making the spell-scar arcana actually worthwhile, particularly in games without a lot of downtime.

Answer 2

This question is going into the minutiae of rules. A spell scar is prepared "using the rules for scribing scrolls." You may scribe "a scroll of any spell that you know." Therefore you must know a spell to make a spell scar of it. In a pathfinder context, what does the word know mean?

"A wizard may know any number of spells. He must choose and prepare his spells ahead of time by getting 8 hours of sleep and spending 1 hour studying his spellbook. While studying, the wizard decides which spells to prepare."

This implies that wizards know the spells in their spellbook.

The knowledge pool ability does not say that you know the spells. It merely says that you can prepare them. RAW I do not think you can create a spell scar of those spells.

If you could tattoo yourself with any spell for the cost of 1 knowledge point and a little gold, your spell book would be nearly pointless. You would be able to build a secondary more powerful spell book on your skin, without being required to search out the spell first.

EDIT: Paizo lead designer Jason Buhlman said about the knowledge pool, "The issue I am seeing here is the ability to prepare a spell using this class feature and then copy it into a spellbook. The intent was to allow you to simply prepare and cast a spell by using up some of your arcane pool."

The other answer differs from mine because we are reading an ambiguous sentence in two different ways. I believe that the only way a spell counts as being in your spellbook, is for the purpose of preparing the spell for that day. This seems to be the developer intent.