I just started a run as a Vampire Skald. Since you start with the book of battle, I saw some neat spells I could learn later on. At level 3 (Maybe even level 2, I forgot to check the book when I leveled up), I was able to learn the Song of Slaying. I completed the floor and I am on floor 2. I immediately encounter a bat, an orc, and a worm. Worms seem to be somewhat tough enemies for me at such a low level. I began fighting and when my health was at two thirds (15 points) I thought "What a great time to see how good Song of Slaying is! This run just started, so if I die, there's nothing to lose!" I cast Song of Slaying with Infusion. I killed the orc in ONE hit and then killed the bat. I then destroyed the worm in two hits. The first hit brought him down to almost DEAD. Keep in mind the fact that I am only level 3, and I had absolutely NO magical weapons and used NO potions!
I'm not sure whether it was the Song of Slaying, the Infusion, or the combination of both, but the book of battle seems pretty powerful at low levels! Please tell me whether this is supposed to happen, or if the book is not so good later on. Either way, once I learn Spectral Weapon, hopefully I could slay anything I wanted at a lower level than normal, such as a group of 4 or 5 gnolls, once I slay the first 1 or 2, as long as I cast all three spells!