Dummy Zombie’s purpose is to just buff scavenger it seems. Can maybe also be used for sacrifice or graveyard shenanigans not sure which though.
Just a short comment to this: What i had in mind was that it synergizes with the Titan card, just like Placebotron does. So it makes Zombie Abomination a bit cheaper. However, you could potentially combo it with Death Blast, SoA Aletha or Necropolis in addition to the scavenger. At least that is what i had in mind for it.