How to kill Black Dragons?

a tested tactic, requires a lot of grinding, little experience, but it works =)

you need to create a squad of 7 creatures and place one in each slot...
in battle, wait for the dragons to fly in, then try to attack them in such a way that the counterattack hits other dragons (within 2 cells)... do this several times (or once, if you can kill the rest), then finish off with the main army...

it's difficult, but possible )