The Tavern

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!

Infusion definitely falls off really hard. I'm not sure about the numbers on song of slaying though.

Nope. You can treat it like a Fireball, a spell that is mainly used against mobs/groups except you need to stay in melee range and swing weapons unlike conjuration spells.

to be clear infusion gives you a buff which adds
2+(spellpower/25)
damage, with a spellpower cap of 25(so 2-3 extra damage, which is significant early on). It is reduced by AC separate from your main attack, so against enemies who have AC it becomes useless quickly. For example, against an enemy with 6 AC, on average it will do no extra damage.

Song of Slaying gives a slaying bonus, like rings or other gear of slaying, which in turn function like weapon enchantment-add a number from 0 to enchantment(or slaying number) to damage, which is not reduced by AC separately like infusion is so doesn't have nearly as much trouble vs AC.
My only real concern about using it is "how much will the extra noise affect me".

Don't forget Song of slaying continuously makes loud noise!

Use it with species w' auxiliary attacks for double the fun!

The book of battle is great! Song of slaying actually becomes more powerful later on when you can expect to fight large groups more and can handle attracting a lot of attention. It's quite dangerous to use early, though. Spectral weapon is amazing early and falls off later, but always remains very good.

But skald is generally a pretty weak background. You need to divert from melee to get those spells, but the spells rely on your melee skill to kill things. And you can't wear very heavy armor or you won't be able to cast them. IE and Wz are stronger backgrounds for a character that wants to fight with weapons and spells

Broadly speaking, I've found Song of Slaying most useful in D, Orc, and the Lair branches (except for Shoals). Most other areas the noise is more of a drawback than the slaying bonus helps, due to either bad terrain, monster density, or a combination of the two.

Song of slaying should automatically stop when there are less than 3 non-wall adjacent tiles. Kill holes and corridors are too strong even without it.