When you are getting your reward for rescuing Thrommel (e.g. Scather), it is possible to also be given a reward option that includes among the choices twelve 1st level wizard scrolls.
I -believe- this option is triggered by having certain possessions of Thrommel's in your inventory. So to get this option, you have to have allowed Thrommel to die and looted him (which many players probably already do just to get Fragerach). I -think- having his amulet in your possession when you get the reward is what triggers this option, based on a clue given during the reward conversation, but it might be anything. So, if you loot Fragerach, be sure to also take his other gear such as his amulet, ring, etc., and have them with you when you get your reward. I know that when I sold them off before going to get the reward, I was not given the option of getting the scrolls, so that adds some weight to my theory.
BE WARNED - allowing Thrommel to die at any point seems to trigger the "bad" ending cut sequence for Thrommel, even if you do ressurect him and get your reward.
Anyway, the 12 1st level scrolls you get (assuming you pick that option) are as follows:
Charm Person
Expeditious Retreat
Grease
Identify
Mage Armor
Magic Missile
Obscuring Mist
Ray of Enfeeblement
Shocking Grasp
Sleep
Summon Monster I
True Strike
Not that bad, since I don't think there's ANY other way to get Expeditious Retreat, Obscuring Mist or Summon Monster I in the game other than to pick them during levelups.
The only other option at the point where you can get the 12 scrolls that was even mildy tempting was a Cloak of Resistance +2. The other rewards were nice but nothing you'd have trouble finding in other parts of the game (along the lines of Longsword +2). So unless you don't even -have- a wizard at all, I'd say go for the scrolls.
Hope this helps
Thanks, Mulligan, for providing the other lists, it's quite useful to those of us who are anal and want our wizards to have as complete spell books as possible
Qwinn