From publisher blurb:
Boom! An explosion rattles the room as a goblin alchemist cackles maniacally.
The Complete Alchemist is the definitive version of our Alchemist class, with more ways than ever to play your own specific brand of mad scientist. It comes with 5 subclasses, including the Mutagenist, which mutates its own DNA with special potions, the Formulaeist, which gets its own unique selection of powerful bombs, and the Xenoalchemist, which uses an suite of grafts harvested from monsters to become a Frankenstein-ian surgical freak.
This book also includes a deluge of new Discovery and bomb options, making this one of the most customizable classes out there.
Last but not least is the Fantasy Drugs supplement, included at the end of the book. Because what else would an alchemist be working on in his spare time?