Archivest's real power:Potential for every Divine spell on a single character.At any time, an archivist can also add spells found on scrolls containing divine spells to his prayerbook, but he must make any rolls and spend the time required (see Adding Spells to a Wizard's Spellbook on page 178 of the Player's Handbook). The archivist can learn and thus prepare nonclerical divine spells in this fashion but the two free spells he gains for advancing in class level must be selected from the cleric spell list.
And Knowledge checks can be lethal in tabletop.