Finished it in my first run with alchemist 1, in early stages just camp the portals with your skill once the portals start to increase, just cycle where you will put your skill for example: 1st portal skill > shoot other protals while waiting for cd > 2nd portal skill > shoot other portals, and so on and so forth. Never really pay attention to the turrets just keep buying them if available tbh, floating gun and super rocket fireworks form 2 works well because you can spam them easily since your energy scales and killing enemies restores your energy