he doesn't turn into a dragon but go to rose cottage and u'll see a patch of dirt wit
flowers around it dig it up u'll find a silver key to repeat this telly out and walk back
in dig up the key again until u get 20!!

he's in the Archon's folly, which you can only get into if you gather all the heroic
souls.
1. The arena champion- either kill thunder(which I did) or go to the arena to search for
souls.
2. The herione- Either kill Briar Rose(pls don't) or go to the oakvale memorial and get
your mother's soul my killing screamers.
3. The old one- Either go to the guild and into the guild woods and kill the guildmaster
(really really pls dont!) or go to the circle of the dead and fight to get nostros soul.
The choice is yours (just don't kill the guildmaster!)

Jack's dragon form is only in the Fable: The Lost Chapters. If you move with the story you
have to meet with him.

Here are the 20 and the TLC's last 10

http://www.gamebanshee.com/fable/silverkeys.php#null

cool