Alchemists are the might heroes of Tower.
"Alchemists are skilled in physical and chemical magic, particularly so in the building and animation of golems. Working their craft builds muscular strength, which makes Alchemists ready learners of military skills as well. Their armor is composed of rare metal alloys created through their skill in alchemy." RoE manual
Alchemists are one of the two might classes, along with Death Knights, that start with a spell book.
As they are heroes of a good town, this allows them to get experience on Altar of Sacrifice and in Grotto for artifacts only.
They cannot learn Necromancy, which means they can only acquire it from Witch Huts (if allowed), Scholars, Seer's Huts, Pandora's Boxes or Events.