you can only send those eggs who can have a dragon inside ( after a while you will ignore them ) , or on quests on fb you can choose to send dragons to get items ,but those are basic dragons you can buy for a penny anyway.
Hellgate Challenges Boss - Oni Dragon, Chesire Cat Dragon, Demon Dragon, Chameleon Dragon, Midas Dragon, Kratus Dragon, Pure Metal Dragon, Zodiac Libra Dragon, Zizou Dragon, Hellgate Dragon (boss)
Now make your own challenges. Challenges should be named after the boss dragon. Before making challenges, try making a list of all dragons in game so you can choose which dragons to put in the tournaments and challenges. Link to all dragons: http://dragoncityguide.net/egg-list/
Spiky Challenge 5 (BOSS) = Legendary, Crystal, Saturn, Troglodyte, Hearts Queen, Cheshire Cat, Pure Terra, Pure Ice, Pure Flame, Pure Metal, Pure Electric, Golem, Krait, Ragnor, Dark Angel (Boss: Spiky)
Now make your own challenges. Challenges should be named after the boss dragon. Before making challenges, try making a list of all dragons in game so you can choose which dragons to put in the tournaments and challenges. Link to all dragons: http://dragoncityguide.net/egg-list/ (copied)
Note: Boss dragons should have 3 elements. However, you may use dragons with hidden-element attacks and have strong attacks. Dragons are 3-gold starred.
Note2: Don't make your challenges have more than 10 dragons. Dragons would get killed for that. Only use 1 legendary for the challenge.
Note3: Dragons are always level 40. Exception: Legendaries, which are 34 so your dragon can't easily get killed. Exception 2: Bosses are lvl. 50.
Note4: You are allowed to use made-up dragons. Just make sure they have an asterisk (*) next to it to be sure.
Note5: Using hacked dragons in challenges, will be blocked from Facebook. Most games in FB (such as Plants vs. Zombies Adventures) have trap achievements, which makes them cheat and get blocked. Once unblocked, dragons are reverted back to lvl. 12 as punishment.
Let's make sure that SocialPoint reads this thread. Also, challenges will be unlocked after level 80.