Magical Theorems & Dark Pacts (MT&DP) is an Old-school reference for all things Magic-user.
The book is designed with what I call "Basic Era" in mind, so the rules from right around 1979-1981 where "elf" is a class, not just a race. Overtly it is designed for Labyrinth Lord. That being said it is still compatible in spirit to 99% of all the OSR and books from that time.
The book itself is 6"x9", black and white interior and 161 pages. So for a "Class" book there is a lot here. There are 5 Chapters covering Classes, Spells, Magic Items, Monsters and a section on using this book with the "Advanced Era" books (and their clones), along with an Introduction and OGL page.
The introduction covers the basics. What this books, what it is for and it's very, very open OGL declaration.
Chapter 1 is the heart of this book really. It details 13 Magic using classes. The two two core classes, Cleric and Magic-User (Wizard) and 11 new classes.
From the product page:
Wizard (classic magic-users with 10 levels of spells)
Elven Swordmage (elves from the core rules – arcane warriors)
Elven Warder (wilderness elves, guardians of their kin)
Enchanter (artists, con-men, and masters of… duh… enchantments)
Fleshcrafter (twisted magic-users that work with flesh)
Healer (compassionate and tough hearth-healers)
Inquisitor (ecclesiastic investigators and master intimidators)
Merchant Prince (elite merchants with spellcasting support)
Necromancer (you know exactly what these guys do)
Pact-Bound (magic-users who sell their souls for power)
Theurge (divine casters who learn from liturgical texts)
Unseen (thieves with an innate knack for magic)
Clerics are as you know them, but Magic-Users are now Wizards (since everyone here is a magic user) and they get 10 levels of spells. The "Elven" classes replace the "Elf" class in the book. The others are as they are described, but there is more (much more) to them than re-skinned Magic-Users (not that there is anything wrong with wrong that). The classes are re-cast with many new spells, some powers (but nothing out of whack with Basic Era) and often different hit-dice and altered saving throws.
Nearly a third of the book is made up in these new classes.
Chapter 2 covers all the spells. Spells are listed alphabetically with class and level for each spell noted (like newer 3.x Era products). There are a lot of spells here too. Many have been seen in other products, but some are new. In any case they are a welcome addition.
This section makes up slight more than a third of the book.
The last three chapters take up the last third or so of the book.
Chapter 3 covers Magic items. There are 28 new magic items with these spellcasters in mind.
Chapter 4 covers some magical creatures. These are monsters listed in many of the new spells for summoning. There are not a lot, but needed.
Chapter 5 is the Advanced Edition conversion materials. It covers HD changes, racial limits and multi-class options.
So what are my thoughts. Well you get a lot of material in 160+ pages to be honest. At 10 bucks it is a good price. For me it is worth it for the classes. Sure we have seen variations of these over the years, but it is here all in one place and they all work well together. The spells are good. At first I balked at 10th level spells, but really they are for the most part other people's 9th level spells, so they work for me.
The magic items are nice, but for me the value is in the classes and the spells.
Who should buy this? If you play old-school games and enjoy playing different sorts of Magic-Users then this is a must have book. If you are looking to expand your class offerings or even add a few new spells then this is also a good choice. Personally I think it is a great book and I am glad I picked it up.