This could be exactly what was wanted - wear any do-gooder's down and out so they're too tired to do anything. In fact that does seem to be the plan, no matter how many of the mooks and creatures Natsu destroys, there are more to take it's place. Though progress is definitely being made - after a point, fewer creatures are available to replace the ones destroyed. Or maybe Natsu's starting to destroy them faster than they can replace the fallen.

By the time the last one has fallen, the voices have stopped - but the scents are still there. In fact there's one very clear scent - straight down about twelve feet, where he'll fine a heavy, thick coffin made of ice buried beneath the ground. And there was someone inside. That's where the thumping had been coming from. Before where the thumping had been constant, it's only once every few minutes now.