Wasn't here going to be a ratling race new to ADOM... or is that Jade?
Anyway, I don't know how an Alchemist would work, unless there was a more advanced form of alchemy for them, but how would they fight? not as fighters or spellcasters, and they wouldn't have the other abilities that assassins and thief have, so what? Agreed, summoners would be redundantly similar to Necromancers. What about scholar though? they would be ok fighters and ok spellcasters with the added ability of automatically having all books and scrolls identified. Maybe Potions to. And immune to IBM and scrolls of amnesia. Give them writing sets with a bonus. At level increments give them an area of study, adding skills like Herbalism, Law, Alchemy, Pick Locks, Detect Item status, Music, Metallurgy, Mining, Gemology or others. also give them the studied enemy ability (like preferred enemy ability of D&D ranger class). Have it be random, chosen or be based on the most killed unit so far in the game. Obviously high int and skill levels. Make them good book casters, but bad spell casters otherwise. Maybe wand abilities to?