Just wanted to verify this as a working combo before I tried it.

If Nightshade gives Klaw B/C/F with her werewolf serum, and Klaw has access to the soul gem, when Klaw activates his power:

SOLID SOUND CONSTRUCTS: Klaw can use Barrier. When he does, after actions resolve, as a free action you may make a single close combat attack that targets each opposing character adajent to any block terrain markers just placed by Klaw. Divide the damage value among hit targets.

Hoping on a B/C/F roll of a 6, and the damage being successfully being dealt to 6 different opposing and adjacent characters. Does this mean that Klaw can steal energy x 6 and heal for 6 clicks?

B/C/F is activated through a close combat action. Klaw's special only works on a close combat attack, you wouldn't be able to use B/C/F through his barrier special.

If it did work though, you would've been able to heal 6 to characters that actually took damage.

This.
On the other hand, Steal Energy works any time the character makes a close combat attack, so if Klaw manages to damage multiple figures with his attack he would get to heal multiple clicks.

Thanks! I'll play with this idea for a bit, see what happens.

Also, thanks for clarification on the Action vs. Attack.