The alchemist class represents a trope common in adventure fiction, if not fantasy fiction: the mad scientist. From Mary Shelley's Frankenstein to The Strange Case of Dr Jekyll and Mr Hyde, many of the classic works of fiction that helped build the framework from which most fantasy RPGs hang include the inventor or scholar who is clearly dabbling in matters beyond mundane science. Coupled with the more fantasy-friendly view of the medieval alchemist who seeks to use combinations of materials and formulas to bring change to the material world and a rich history of inventor-adventurers dating back to Daedalus, the alchemist class allows players to enjoy an archetype that can't easily be represented by any other Pathfinder Roleplaying Game character class.
However, that rich tradition of mad scientists and natural philosophers obviously requires much more support than any single book has room to offer, especially since most game supplements have to appeal to a broad range of interests. The Advanced Player's Guide lacks room to present alternative alchemist options, and logically it must focus on the most obvious and functional discoveries and bombs. But if ever there was a class that called out for quirkier possibilities, the alchemist is it.
To help in that regard, Advanced Options: Alchemists' Discoveries presents 29 new discoveries, including 7 tied to two new forms of alchemy: spagyric devices and metamorphosis. With this broad set of new options, alchemists can make rockets, create homunculi, sniff out their foes, craft waxwork wings, and even transmute lead into gold.