I am the GM of a newly starting Skull and Shackles campaign. One player was interested in playing a mad scientist kind of character, but also wanted to be a necromancer. I suggested Vivisectionist or Reanimator, but they weren't good enough at necromancy so we settled on the Undead Lord archetype. I'm not sure how we found Haagenti after that, considering he isn't a death domain deity... I allowed it for now, and I really like the deity.
The current build has 16 Int but only 13 Wis and 8 Cha, pretty bad for a cleric, dire for a necromancer. I've seen the unchained multiclassing rules and currently I think that's the only way to save the concept...
Are there any other alchemy-themed archetypes or domains for a cleric? Or is there a feat tree that would keep the mad science theme? Is brew potion the only thing required? Or would Technologist possibly work as well?
Or should I suggest a different deity?
A worshipper of Haagen Dazs ? Lot's of ice spells, so you need something about cold magic.
More seriously, the construct domain could be used for something like a Frankenstein cleric.
The protean subdomain seems to have potential, as well as radiation and insanity subdomains. Your player should keep at least one death/undeath related domain, like the undead subdomain.
I built a worshiper of Haagenti once. Never got to try it out though.
Basically, it was an Oracle of the Dark Tapestry. Really good at level 20 with Shapechange and free healing.