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The Death Blast is a feature unique to the Zoids: Wild franchise.
The Death Blast is a forced activation of a Zoids hidden potential, and is functionally equivalent to a Wild Blast.
The slot that would normal require a Zoid Key to activate, instead requires a Death Metal Key, and has a housing apparatus placed over the opening.
The Death Blast is performed solely by the Death Metal Empire. By using their technological resources they manage to invent the mechanism that allows them to unleash power similar to a Wild Blast, but without need for a strong bond to form between the Zoid and the person riding it.
The technology is imprecise, and much of the series is spent perfecting it.
In the anime, Onigiri is seen in episode 7 to be assisting the Death Metal Empire with researching these keys against his will. However, after he is rescued by Arashi Death Metal's research is set back significantly. It isn't until after episode 39 that they are able to begin a mass-produced rollout of the keys.