ALL opposing characters? Are you telling me Blockbuster hitting a guy with an object can strike fear in Nekron?

This guy belongs in the Sinestro Corps. His costume is scaring everyone.

So if he hits a wall does the power still work?

Does it read "character's defense values" or "characters' defense values"?

It looks like a typo, but would be a huge difference. For those who don't see where
I'm going with this:
character's = singular possessive
characters' = plural possessive

While your question is totally justified, wording is 'all oposing character's' so you modify def value on all oposing figures. Think of ot this way - he punched someone so hard and so messed him up so much that other characters just stand there terrified making them an easier targets;)

@Briscoe: From the Wizkids E&C:
HITS
[C]A “hit” is when one character makes a successful attack against at least one other character. Successful attacks against objects or terrain are not considered "hits".