Victory or death. If that doesnt give you a clue of how the Mardu Horde thinks, I dont know what will
They're legal for play (if format-eligible) and highly sought after by collectors
As long as your Goblin Welder doesnt have summoning sickness, you can simply tap this pesky little critter, sacrifice your Zuran Orb, Fountain of Youth, or Claws of Gix, and pop that beefy threat into play extremely early in the game, putting you well ahead of your opponent
It's especially fearsome in blue, which has lots of card draw effects and can make the most of the extra mana when its given
They're black Zombies in addition to their other colors and types
And you're probably already running Altar of Dementia in a Sidisi, Brood Tyrant deck, and this is one more way to pop off with that