Alchemist is definitely one of my favorite chars, but I think it needs some serious reworking. The signature mine spam looks amazing on paper, but in practice, it is actually very difficult to get enemies to run over the mines when you are actually playing with the whole team because 90% of encounters have most enemies die before they can run over the mines even from ice flask taunt, aside from 5/5 chokepoint mine spam.
It is actually very difficult for alchemist to survive at higher difficulty levels while doing her mine spam, which requires that she stand very close to enemies and start throwing mines for anywhere between 5 to 8 seconds, depending on whether or not tonic duration passive was used. And ice flask doesn't work while it is mine throwing time, and imo 5 seconds is way too short for the ability. 5 seconds of 85% damage reduction when your other abilities are for stealth, flask of fire, and elemental mines, means 3-5 seconds of weak basic attacks, after which enemies will destroy you for being so close to the front lines unless you go back into stealth and wait for more mine spam.
If it was possible for alchemist to keep on running while throwing mines, she could litter the whole battlefield with them very quickly before the rest of the team wipe out all the enemies, and that would be significantly better than having to choose between throwing 5-8 times in a single location where 80-90% of the mines won't be triggered, or 2-5 mine throws so that the mines can be distributed more around the battlefield but take a very long time to deploy due to all of the animation delays from each individual throw and delay in animation before you can begin running again.
Again please don't see this as me trying to diss alchemist, I think the character is cool and gameplay is good in theory, but in practice she is probably the weakest class in the game due to the difficulty of actually safely and effectively using her signature attack.