This pdf is 23 pages long, 1 page front cover, 1 page editorial, 1 page ToC, 1 page SRD, 1 page back cover, leaving 18 pages of content.
The pdf begins with an aptly-written IC-introduction followed by an explanation of the new mechanics. Essentially we get a new type of damage that can be combined with another energy type. Thus, e.g. purifying damage could also be combined with cold or other energy types. Due to the rich tradition of cleansing flames, this book uses flames as the base energy. The purifying energy damage is susceptible to the immunities or resistances of the base energy as normal. More importantly, purifying damage only deal damage to evil creatures (though, with a feat, you can also damage neutral creatures.)
The first part of this book portrays the new [Purification]-feats. These feats work a bit like metamagic feats in that they are applied to spells. However, unlike metamagic feats, they don't increase the caster level. You can only apply one purification feat per 2 levels of the spell, rounded down. Usually, non-evil creatures gain an additional benefit from being in the area of effect of a purification-spell.
The 25 new feats are:
-Abolishing Fire: Dispel evil (third effect) on target
-Abolishing Fire. Greater: As the normal, but dispel more
-Banishing Fire: Banishment for evil outsiders
-Clarifying Fire: Remove Blindness/Deafness
-Cleansing Fire: Remove Disease, temporarily suppress disease-ability of enemies
-Discriminating Purification: Damage neutral creatures as well with purifying damage
-Disparaging Fire: Frighten enemies
-Dispelling Fire: Dispel Magic
-Dispelling Fire, Greater: Greater Dispel Magic
-Disruptive Fire: Destroy evil undead that fail a DC 17 fort save and have less HD than you
-Exhausting Fire: Exhaust enemies, afflict undead with light or severe necrosis /see Liber Vampyr)
-Extra Ignite Weapon: +1 Ignite Weapon per day
-Fortuitous Fire: Remove Curse and temporarily disable Curse special attacks of enemies
-Invigorating Fire: Remove Paralysis
-Mark of the Purifying Flame: Gain bonus to diplomacy and +1 damage for purification rolls
-Melting Fire: Stone to Flesh
-Neutralizing Fire: Neutralize Poison, enemies temporarily lose poison quality
-Pure Conviction: +50% damage via purification against evil creatures. OUCH. That's powerful. Very powerful.
-Purification Mastery: Apply +1 purification feat
-Purifying Spell[Metamagic]: Makes a spell a purifying spell, +1 caster level for good casters, +2 for neutral ones
-Purifying Strike: Deal an additional +1d6 fire/purification damage via your weapons, can be used Cha-mod times per day, min 1/day. No duration is given for the additional fire damage against the designated target, though.
-Relentless Purification: Ignore your character-level resistance of enemies towards your purification spells
-Restful Fire: Lets non-evil creatures stave off fatigue and exhaustion
-Soothing Fire: Remove sickened condition of non-evil targets
-Greater Soothing Fire: Remove sickened and nauseated conditions of non-evil targets
After that, we get 19 new spells, some of which can be added to the spell-lists of the APG-classes. Good to see that they are not forgotten. The new spells all have the [fire, purifying] descriptors.
-Blinding Embers (Clr 4, Sor/Wiz 4): 3d6 + blindness or remove blindness/deafness
-Brightflame (Sor/Wiz 2): Burst 3d6 + daze evil creatures
-Enshrouding Flames (Clr 2, Sor/Wiz 2, Sum 2): persistent 1d6 damage to foe or minor burning shield
-Fires of Clarity (Sor/Wiz 8): Cure confusion and deal 1d6 damage per caster level, cone
-Fires of Redemption (Clr 7, Sor/Wiz 7): 5d8 damage, can work as atonement and cure diseases, poison and curses. I'm going to talk about this one in the conlcusion.
-Fires of Wrath (Sor/Wiz 9): 1d8 per caster level damage and 1d4 negative levels for evil creatures that fail a second save.
-Heartfire (Clr 6, Sor/Wiz 6): Sickening ray that deals 2d8 per caster level.
-Holy Inferno (Sor/Wiz 4): Cylindrical fire, 1d4 per caster level, slows evil creatures without a save.
-Moonflame (Brd 1, Drd 1, Wch 1): Light to make evil creatures shaken, can be discharged as a touch attack.
-Persevering Blaze (Clr 8, Drd 8, Sor/Wiz 8): 4d8 damage per round for evil creatures, can heal the same in good creatures
-Pureflame Barrier (Clr 6, Sor/Wiz 6): Holy flame wall, especially effective against undead and evil outsiders
-Pureflame Ray (Clr 5, Sor/Wiz 5): Ray deals 1d8 per two caster levels and staggers enemies, especially efficient against undead and evil outsiders.
-Rebuking Flames (Sor/Wiz 7, Wch 7): burst deals 1d6 damage per level, enemies must succeed a will save or cower.
-Revitalizing Inferno (Clr 9, Drd 9): I think there is a glitch here: This spell deals only 1d6 points damage. Secondary effect is to act as Greater Restoration and Regeneration for good-aligned people who stand a minute in it.
-Sacred Combustion (Clr 3): 1d6 per caster level damage or heal.
-Sacred Weapon (Clr 3, Inq 3, Pal 3, Sor/Wiz 3): +1d6 purifying flame damage. I think there is a typo here, the duration of the spell should probably not be "instantaneous".
-Transcendent Immolation (Clr 5, Sor/Wiz 5): Get a fire shield and bonus to saves against diseases, poisons and curses.
-Whitefire Ray (Clr 1, Sor/Wiz 1): 1d6 ranged touch rays, 1 ray per 5 levels.
-Whitefire Ring (Sor/Wiz 3): 10 ft burst centered on you, 1d8 per to caster levels (max 5d8), push enemies away.
After these, we get a new PrC, the Knight of the pure Flame. The knight gets d10, 2+Int skills per level, proficiency with any armor and weapons, a good BAB, medium fort and will-saves.
The PrC focuses on an interpretation of a holy knight who infuses purification damage in his weapons. I liked the class and it didn't seem to be OP. the PrC-write-up is detailed and features roles in the world etc.
I've gotta come clean about one fact first: I HATE the alignment system. From the bottom of my heart. In each and every campaign since my first, I've replaced e.g. detect evil with detect heretic, thus making both smite and the respective spells stronger put also potentially deadly to good guys caught in them. Thus I have to admit that I, personally, reject the premise of universally good, discriminating damage. On the other hand, I love the trope of cleansing fires, especially how the holy flames harm only those who do not adhere to the sacred principles and the PrC is a godsend (bad pun, I know)for one of my players. Additionally, the spell that acts as atonement is just not my cup of coffee. However, even neutrally, there are some problems I see balance-wise in this pdf, namely the fact that in most campaigns, PCs will fight mostly EVIL enemies. Demons, Devils, corrupt governments, warlords, goblinoids, you name it - all evil critters and the abilities of these feats and spells are STRONG against these. Even worse, there is a feat that makes it possible to target neutral creatures with the fire, too. The whole book draws alignment-wise a VERY clear b/w-distinction and while some of text mentions moral ambiguity, shades of grey campaigns will find themselves VERY hard-pressed to uphold moral conundrums, when purification damage and effects are such a godsend towards the pure souls, even more so than with the standard spells. On the production value side, I noticed some errors which another pass at editing could have cleared. The one piece of full color artwork is stunning. Layout unfortunately adheres to the NWN-standard, i.e. we once again get the rather printer-unfriendly used-parchment look. Due to my minor balance concerns, the minor glitches and the fact that the book didn't utterly blast me away, I'm going to settle for 3 stars.
P.S.: I actually AM going to use the spells and PrCs. For my villains. A new organization rises, exterminating evil without mercy and while the populace seems to love them, they slowly become more fanatic, routing out minor evil-doers and slowly extending their focus to druids and the like, too, alongside a twisted war-mongering rhetoric of a new kingdom of "pure" beings to inherit the earth. Feel free to steal this angle. :)