I see people are having issues with certain dragons. I took them all down with the following:
Dueler - Apprentice
Bronzetalon - Dreamweaver
Rainbow Sentinel - Quetzal
Watermelon - Music
Germany - Mage
Messenger - Aether
Prime Arcane and Prime Void - Apprentice
Pokey - Queen
Full results with the combos I used are on page 2