Grimrock

...I first encountered those on Hamlet beach. I tried everything I could. Weapons, magic. Electricity seems to heal them, and everything else does 0 damage.

Has anyone managed to bring them down?

Those are Air Elementals, and there are a couple other posts about this topic.

Method 1: Method 2:

Thanks. I... have two leftover skill points for my mage, but am hesitant.

In the hamlet, before I had any methods of killing them, I would lure one to a corner of the map and then run away. This allowed me to complete puzzles in the other part of the map while it was roaming about on the other side.

In the underwater vault in the middle of Sleet Island, where the water shrine is, you can get a rod that casts dispel as well. need a gold key.

the ethereal blade is actually fairly easy to get, it's in the cemetary. just be ready to kill a few above average undead (about twice as strong as a mummy).

I didn't discovered any "legal" method to dispatch that creeps and just telefrag them It is pretty easy, but drawback is zero exp.