So I'm much to lazy to find it, but I remember something here talking about Aluminum negating the power of time bubbles. Because of this, I came up with an awesome possible villian idea.
A villain originally thought to be an extremely powerful steelrunner, this is a monster, leaving a room full of corpses before anyone knew what happened.
Eventually, it is revealed that this is Slider(Cadmium misting) who has amassed enough aluminum to make full armor and knives. With this he can put up a cadmium bubble; freezing the whole area, but not freezing him because of his allomancy negating armor.
Because of this, he can go full speed while everyone else is frozen in place, running around with a runny-runny stabby-stabby rampage.
So, assuming my imagination is not completely stupid. Cadmium could actually be cool!