The Dragon is weak!! It's not very useful; they should have lowered its price and increased its stats. Otherwise, it's not a strong melee unit and can't win through numbers.
Zubr, it seems your opinion has changed... Tell me why? As far as I know, you've started to prefer the Mech Dragon. In a tournament game against Aro, you were building them... Or did you regret it later?
I think that against Nature, you should take Monks instead of Crusaders.
Monks (if they have accuracy, of course) can take out the hero on the front line with the first shot (usually the Nature general (Tactics + Warfare)). If he was under Immortality and drinks another potion, the Angels finish him off (or vice versa, if the Angels go first).
Monks are strong units, but I've also started to prefer Crusaders lately. Because even most of the Life spells are more geared towards infantry, towards attack... And it's unlikely that the general will be on the front line... Although there's a chance, of course, but not always.