If you mean by the 'Death Machine' it is a turret you put in your hand and just shoot automaticaly.. (; how you get it is that its just like getting a nuke , or a ammo. It just automaticaly appears.
Crazy Dave
Theres actually a quite complex story behind it, and i am sorry that i can not list all the details but look up: Cod 5 WAW Zombies Storyline. It explains how a crazy scientist made the zombies and the hellhounds.
It makes all inactive mystery boxes active and they all only cost 10 points. Go Crazy!
You can buy them from Crazy Dave using gold.
The cast of Plants vs. Zombies - 2009 includes: Orion Acaba as Crazy Dave
you buy them from crazy Dave
to black crazy daisys and a roxy seed
Using a Black Crazy Daisy, you can get : Shi Shi (Red Dragon, Yellow Hot Silly, Black Crazy)
Buy it from Crazy Dave after completing Adventure Mode.
Samantha's Hairy bush!
cheat it
I.G.G.Y has 3 black crazy daisies too.