An actual Alchemist. Singed doesn't really count. However I did find it funny that his ulti duration was influenced by the Time-Warp Tonic Rune.
Anyways I'd like to see one that can actually drop potions that boost stats, much like how Zoe's W can make minions and champions drop summoner spell and item actives. Instead can drop potions by him or herself. She has a healing cask similar to that of Ana from OW and can be splash much like Twitch's. Can affect towers as well.
Her ultimate could be like Rikku's Mix from FFX, when ulting, presseing keys QWE in certain orders will grant a boost to an Ally or create an AoE move against enemies.
The concept might be a little over the top. And there are ways to simplify it I'm sure. But that's something I'd really want. I'd like more hextech-y champions but not necessarily body augments or steampunkish weapons. Really an enchanter with a science-y background.