Any thoughts on how to enter Cet's final resting place without Lavawalk? I have tried hopping on the stepping stones but I am wiped out before I can use either of my Champion Keys. I think it rather disappointing to get to the last room only to find out I can't finish the game because I didn't have the foresight a month ago to stick with Stone magic until I got lavawalk. And because I have already saved Kerah's soul I can't leave the pyramid to get lavawalk.

Seems a tough jam you are in, but I think I recall someone getting out of it. I think the potential cure is to select someone with good HP and the raise dead spell. Cast many many toughen spells on them, so you raise their HP to like 500 or 1000 temporarily. Now get that character to run to the doors and use the keys, and once open, nip just a little way inside the corridor. Now raise all your party back to life before going down and talking to the big dude. Hope it works, let me know.

Though I also didn't have the foresight to stick with Stone until it got useful (Sun always worked so much better...), I had gathered 3 or 4 Lavawalk *scrolls* by the time I reached the end; it only took one to get through there.

I found lavawalk scrolls to be plentiful in the tomb, you can find them in the chests, or sprites or fiends will drop them (or you can pickpocket them). I think they purposefully made lavawalk scrolls available in the tomb in case someone didn't get the lavawalk spell. Turn the spawn frequency up to maximum and walk around killing things until someone drops a lavawalk scroll.

And over on the left is an amulet with 50% protection from fire, plus you can use dragon armor (if you kept any) to help. I don't know if any of the armor spells will help, though.