The Helldozer is a visage of horror that instills the impulse to flee and the need for a new house. While it may seem like all it does is wreck the city (which is true), the reason for its wrecking rampage makes it an unlikely champion of the citizenry. The Helldozer exists because of the guilds. None will claim it because it's too hard to control, but it most definitely is the product of the guilds, both physically and (if you can say this about a zombie) mentally.
The helldozers were created in a joint venture between the Golgari and Orzhov, the two most business-oriented guilds, to be used as one-giant demolition teams. They would be cut loose on decaying neighborhoods in need of “reclamation.” Sometimes, the inhabitants would be notified of the demolition. The Orzhov would control all contracts on the rebuilding of the reclamation zones and the Golgari would claim all dead that result from “accidental” loss of life during the demolition. Nasty, nasty guilds. Nasty even to the helldozers themselves. The 'dozers were tortured, mangled, and forced to “work” amid the harrowing cries of innocents being crushed beneath the weight of guilded rubble.
This sort of treatment works fine on a person with fear of death. Being that they are already dead, this treatment ended up backfiring on the guilds. The angry 'dozers stopped listening to the puny guildforemen barking orders at them. They stopped heeding the command of the guilds entirely. But, they did not stop smashing stuff. Their minds were twisted and bent on smashing stuff. Now they're uncontrollable and nearly mindless. There is just enough left going on in their little tortured brains to take special pleasure in the smashing of guild properties. It is this tiny glimmer of anti-guildhall mentality that makes Helldozer a favorite antihero among downtrodden Ravnicans.
Sometimes you go to hell, and sometimes hell comes to you.