The wording of the Bendalloy/Cadmium bubbles seems ambiguous to me: Are bubbles necessarily extended in a sphere with the Slider/Pulser at the epicenter when they are put up, or can you put up an oblong speed bubble, allowing you to run in a line between point A and point B without allowing enemies nearby in? The rules say that the bubble is centered on you, so that seems to indicate that it's a sphere, but I'm not sure.
Also, when can you put up a speed bubble? If you can put one up at the end of your turn, and then keep it up until your next turn, that gives you a heck of a lot of extra dice every single turn. Seems a bit OP, to me. But the alternative, forcing you to concentrate to put up a speed bubble, reduces it's utility to near 0, it would seem. Am I interpreting things totally incorrectly, or have you all encountered this as well? If the latter, what did you do about it?