Claudio Stacciarini

blackpixel
What this bias essentially is, is a blend between your attribute and 1.0.
So you can easily build your own bias with a wrangle or point VOP

You are also not limited to Cd and it's a good practice to use your custom attribute to do what you want.
There are some nodes that override color and it might get you in trouble at some point.
And in the case of the density attribute: you just need a float, so there is no need to store a vector.
You can always preview any attribute with a visualizer or a Color SOP ( ramp from attribute )