Counter-heroes in duel mode (3.1).

Thank you. Does Axel have a counter-strategy for this tactic used by Daedra?

No, if Daedra manages to heal her dragons after depleting all of Axel's mana (adepts), then it's game over. Even if Axel gets very lucky with the dice rolls throughout the game, he will still lose (with such a tactic from Daedra).
In my replay, I think it would have been more effective to upgrade archers instead of paladins, which might have given him a better chance. But still, it's a loss.