Because on Innistrad, they have a zombie problem. And they put the cages around the coffins, so that when the zombies wake up, they can’t get out. Note, that’s a when, not if. On Innistrad, they will wake up eventually.
Maybe this is a dumb question, but why not just make the actual coffins out of something sturdier? Or maybe shackle the corpses? Or what about cremation? Save yourself the trouble of buying a coffin at all, let alone a cage for it, and you don’t have to worry about zombies. Just an idea.
Forgive me if I’m skeptical, though. These are goblins we’re talking about. How does that even work, anyway? They melt some artifact down in a vat of caustic…who knows what? And out pop more goblins? I probably don’t want to know.
According to the MTG Wiki, the Ashmouth is a demonic gateway, taking the form of a magmatic chasm (hence the card name) in the Geier Reach Mountains of the province of Stensia on the plane of Innistrad.
Now don’t get me wrong, I’m as big a fan of fiery hell-pits as the next guy (that was sarcasm; also, why do I feel the need to mention that?). But as you can also see, the mountain roads near the Ashmouth do not have proper guard rails. This makes the time-honored tradition of driving your carriage through the country-side at breakneck speeds–as one does–much more dangerous. The fellow here careening over the edge seems to have found this out the hard way. Safety regulations appear to be somewhat lax on the plane of Innistrad.
Pretty sure it is, anyway. Guess it’s kind of hard to tell. You know what, though? It being made of something else doesn’t really improve things much. I still don’t want to run into one of these. This thing is huge.
I feel like I’m not being overly cautious when I say that I don’t want to be messing with anything called a ‘Nihil Stone.’ I mean, just read the name. This isn’t the Stone of Rainbows and Happiness. Or the Stone of Everflowing Ice Cream. In fact, I’d wager the Nihil Stone and the Stone of Everflowing Ice Cream might have trouble coexisting. And if I have choose between nothing and ice cream, I’m picking ice cream.