Alchemeister

The Alchemeister is an alchemist that is more skilled at crafting and using the items they craft. Detailed Finish is a good final action when crafting, giving you a higher average at no cost.

With Infuse Potion you are able to heal with potions without requiring your allies to drain their own mana, making you a lot more effective as a healer. You don't have to use it every time either, allowing you to make others pay with their mana when yours is running low.

With Counter-Potion you are able to use an alchemy item as a reaction, allowing you to do a variety of powerful things. You can toss a flashbang to interrupt an action by lowering their AP, toss a slowing flask when an enemy is about to approach your ally or toss a molly when they've finished moving to make them take guaranteed damage. Combine this with Quickdraw Alchemy from alchemist and you don't even need to prepare this action in advance. At any point you can quickdraw what you need and toss it.

Secret Art: All of Creation is a situational ability. Changing the damage type will not always be useful, but it can really help amplify damage dealt when against an enemy with a vulnerability or weakness. It is also completely free, apart from taking up your one secret art per encounter. Special Mention goes to Alchemist belonging to a race that can absorb a certain elemental damage, such as Salamander. A Salamander alchemist can force any big attack about to hit them to be fire damage, which they can easily absorb and turn into healing for themselves.