You can bomb the mummies to actually kill them - bombs also work well for quickly finding the exit to the next level by bombing clusters of rocks.

I usually just cheese the skull caverns with a bunch of staircases though. Feels a bit like cheating, but ConcernedApe put the assets in to be able to do it so I did! It’s great for very quickly getting to lvl 100 and then continuing on to farm iridium.