[APG] Lore Oracle, Arcane Archivist (Su) question

[ArVagor]

The Arcane Archivist (Su) revelation states:

• "Your experience with lore-filled
  tomes has granted you the ability to cast arcane spells as
  if they were on your spell list. Once per day, you can cast
  a spell from the sorcerer/wizard spell list as if it were on
  your list of spells known. The spell consumes a spell slot
  one level higher than the level of the spell. You must have
  a spellbook containing the spell to cast it in this way, and
  the spell is erased when you complete the casting."

Can "the spell is erased" be clarified? Is it gone for the rest of that day, or gone from the spellbook for good? If the latter, it doesn't seem like that useful of an ability unless you have a wizard on retainer to continue to scribe new spells into a spellbook for you...

[xellos]

Same question- would an oracle character need to keep a blessed book and a wizard on retainer? ^_^;

[Sean K Reynolds]

Erased means erased. It's gone.

However, keep in mind that scribing spells into a book is VERY cheap in Pathfinder; even an 8th-level spell is only 640 gp. So, by the time you could use this ability on 8th-level spells (requiring a 9th-level spell slot, thus a level 18 oracle), it's chump change (an 18th-level oracle PC has 530k gp). By comparison, an 8th-level scroll is 3,000 gp.

[JoelF847]

Not to mention that it's a pretty good use for captured enemy spellbooks after a party wizard has copied what he wants into their own books.