Board Thread:Dragon City Gameplay Questions & Answers/@comment-14062297-20130815225921

Use a level 8 Armadillo dragon OR a level 8 Pirate dragon. Their stars don't matter.

Why? These 2 dragons (and only these 2 AFAIK) at this level can kill Thor/Loki/Odin dragon with 2 attacks AND they can survive 2 attacks from Thor/Loki/Odin.

Which means that even if you attack second you will still win the fight.

Credit goes to another user who described his strategy for beating special event dragons in another thread. I used what he described to do my research. 