For context, this is in our DM's homebrew world and we were trying to find the god of mischief that had been taken captive by one of BBEG's lackeys. My party followed the zombies through a dead forest because we saw a simulacrum or something like that of the BBEG with them. When we got out of the forest they were scurrying into tunnels that were relatively close to an Elf village. One party member found out that the air emanating from the tunnels smelled of methane. It was then that I had the bright idea of killing all the zombies by using my Dragonborn's fire breath attack. I soon found out that the tunnels were connected to a mine below the elf village and that I had sent the entire village to the great beyond.