do you have phantom spell? Phantomed units are good and are like you casted target on them
Demons or executioners are also good, 50% fire resistance, furious, cast divine armor and dragon slayer on the stack, cast that pentagram of theirs and watch the magic happen
btw if you don't use phantom and bring archers of any kind to fight dragons, you can pretty much say good bye to them unless you are going to waste all your casting on trying to save them/protect them/ress them etc. I wouldn't bring any. Well, depends what kind and how much dragons are you going against, if you are going to fight lots of other stacks and there are couple of dragons there, than I don't see a big issue, phantom some unit (other than archers unless archers are going to play before dragons, which is unlikely) so that dragons would target it instead of archers, cast dragon slayer on your tank that is going to be killing them, if you don't have dragon slayer spell, cast helpnessnes on dragons (unles they are black ones, you can use plague on black ones, if you use demons, demons are not affected by plague)