one of the choices after a dragon kill is adding forest fights. I'm at 26 DK's, and I've added 8 fights. I never run out.
Shun, my clan leader is going to contact you on lotgd. She's awesome! She's one of the strongest players on the site. She's the one who brought me into the clan, and got me started. The bonuses and stuff you get as a member make the game go a whole lot faster.