Tactical techniques for conducting battles in Heroes of Might and Magic II.

I understand. But as a universal tool for defeating elementals, especially on Impossible difficulty, where you usually barely have enough resources for one hero on the first day, I wouldn't recommend it. It all depends on the map. In Beltway, as far as I remember, you start with two heroes, and there are chests, so you can take advantage of that.

We played a championship on Dungeon, and Beltway was one of the five maps... I actually took 1st place there.
Everyone was surprised how it was even possible to get green dragons on the first week.
Some even asked for a step-by-step guide – if you're interested, look it up.

So, nothing is impossible.

And regarding the first day – if you start with a Warlock castle and build gargoyles... how many more units and gargoyles will we have? ;)