Savage grin

So, here's my report.
I completed the map on 4-3-1 difficulty (in 99 days).
It wasn't without a bit of trickery – I had two almost identical heroes: Mullich and Gunnar. First, on 3-3-1, I attacked with Mullich, taking all the slots with 5 Azure Dragons each. Considering his special ability and cloak, he had the highest initiative, and with Berserk, he wiped out all the enemy troops except for the stack of Azure Dragons. (After two such raids, I paid them off each time without any losses). The Azure Dragons didn't decrease in number.

Then, I decided to build up my army, and during this time, I cleared the remaining territory of the Rampart faction and leveled up Gunnar (I wanted to use him in the final battle, as he had better skills – Mullich couldn't get the Defense skill). The two huts with the +5 attack quest were very helpful here.

At the same time, I continued to monitor the castle with Lucifer.
And what did I see? This idiot AI filled all its slots with junk, and left the stack of Azure Dragons in the castle. I immediately rushed there with Gunnar and punished him, then I finished off the Azure Dragons in the castle with a zero-level hero.

Would Lucifer have defeated the Azure Dragons? – I don't know, maybe, but with significant losses.

So, it seems that my strategy was similar to that of A_l_e_k_c.

Added after 3 hours 59 minutes

learn new useful spells...

I placed the Grail in the Conflux in the underground. So, I got all the magic (except for Flight and Direct Damage, which the map author probably disabled)