Welcome back to Ravnica’s sewers, folks. This one’s kind of gross. Seems like a really bad way to go. Also, that poor horse! Based on the flavor text, though, it sounds like rot farming is a thing in Ravnica? So, it seems safe to assume that there a nontrivial amount of these sorts of filth pits sitting around that one could fall into. And if you fall into one, you’re going to be in a real bad spot.
Come to Ravnica. Join the Boros Legion. Fall in a cistern. Die.
10,000 Reasons Why the MTG Multiverse is a Terrible Place to Live 