So I just figured out how you can use acid from one of the spitting slugs to melt fulcrete walls. You just pour it over the point you want to penetrate and wait for a few turns. It seems a little broken, that a fairly easy-to-find trash substance negates the purpose of those rare and expensive colored card keys. Maybe, for balance, you should need one of the glass vials to hold acidic substances, and consequently be limited to a few drams per vial?
I feel a little stupid, I only put two and two together once I noticed that the honey skunks acid-gas, if correctly baited, would easily melt entire sections of fulcrete. Now, whenever I notice a spitting slug I make sure to grab at least thirty drams of the good stuff.
I also found one of the artifacts, so spoilers below:
This is kind of a lame spoiler because I forgot the actual name of the thing. I was wandering southeast of Joppa when I noticed a three-tile forcefield emanating from one of the snapjaws. He was fairly easy to kill despite this, in fact as I approached the overly-confident warrior the forcefield sputtered out, and one he fell he dropped a 3-armor named shield! The read 's'tory feature was awesome, and gave a sense of weight to the red-and-black shield I've only seen in one other roguelike, Sil. The fact that a rando snapjaw had managed to secure ownership of the artifact seemed all the more appropriate considering it's colored history. I imagine the little guy finding it under a bush or something arbitrary, and parading it around for all his friends. Of course he had nearly depleted the chem cell by the time I found him.
I still think traipsing mortars are bullshit aha, I've lost more characters to their walk-around-the-corner-oneshots than anything else.