See IceHot's post above.

Bouncing Beast is the way Fly-By probably *SHOULD* have been worded, but wasn't.

Beast will automatically break away, so unless he is trying to move away from a character with Plasticity (or something else that prevents automatic break away) he will not need to worry about rolling.

ah yep thanks guys.

I have HSS, 0 range.

I smack a guy up close with no Plasticity; before I move away, he clicks onto a click with Plasticity.

Am I now required to roll breakaway?

No. As said above, break away is only rolled when your character meets two requirements: A) It is given an action to move and B) it starts said action adjacent to an opposing character.

Those conditions are not met in your scenario.

Note, however, that if your character moves adjacent to this now-Plasticity-having character, it will have to stop moving. Like so:

. P .
. H .
. . .

If H (Hypersonic Guy) moves into any of the red squares, he will be moving into a square adjacent to the P (Mister Plasticity) and be forced to stop.

So, hit, click, see that he now has plasticity, and "back away" when you continue your move action, don't move into one of the red dots/squares.

I give you a 10 for that lesson

<RurouniX >Notice how they discriminated against the BLACK MAN??!??? </RurouniX>

But that M+M Archangel tho