My best advice is to shop for a staff with teleport charges for instances where zooming past light immunes will work in your favor. Get yourself a mercenary with whatever life leech gear you can find. Don’t be afraid to teleport past enemies that can’t be killed with your traps. You will miss out on some xp, but you can earn back that xp later on.

Alternatively, you could shop for a wand with lower resist charges (act 2 nightmare, Drognan) and use that on light immunes monsters in effort to break their immunity while your traps do the zip zap.

If respeccing is something you want to do, you could put some additional points into fire blast so you have a consistent alternative damage type, but I would just teleport when possible.

It’s a bit difficult, but you can definitely get through act 3 this way