valukr said:
So for example:
I declare i'm attacking with 2 str for the axe, and my opponent declares a 3 str character to block, the defenders have now been declared can i now use great umber ability to participate in the challenge?
This is, in fact, the most common way to use Greatjon - adding him as a participant (and STR) to your side of the challenge after all attackers and defenders have been declared. And it is especially useful when you are attacking. So yeah, you've got this card down cold!
The rest of the thread is really about some of the more "creative" ways to use Greatjon. Your example covers the basics (and probably 85% of his use) very well.