blueskirt42: Oh, not at all. The rest of their army is just as overpowered. Centaurs, plus the fast and cheap fliers like gargoyles and griffins can deal with most ranged monsters except druids and trolls.
As for every other monsters, you've go the hydras: As much HP as paladins and cyclops, attacks all hexes around themselves and no retaliation. And this is Heroes of Might and Magic I, the AI is too dumb to know it shouldn't swarm hydras. You know what happens when you pick a single hydras stack in a fight against flying monsters? The fliers swarm and attack your hydras, your hydras tank the blow, sometimes one dies, then they attack, all hexes around themselves, with no retal. It switches back to the enemy's turn, their first unit attacks, your hydras counterstrike, all hexes around themselves... Do I need to continue? It's the first round that's difficult, but if your hydras can survive...
A barbarian or knight with an army of six Hydras can destroy most low-mid level melee and flying monsters. Ten hydras and you're good to tackles the ghosts that guard haunted gold mines, graveyards and sunken ships. With fourteen hydras you're almost guaranteed of defeating most melee and flying monsters with no losses, although by then you should already have your dragons.
To gain an extra edge and possibly attack stronger monsters will less hydras you can also carry a single cheap fast unit like a gargoyle and a spell book, on your gargoyle's turn you cast a buff (bless or protection) on the hydras, have the gargoyle suicide themselves on the enemy and have your hydras save the day.
And since hydras can survive on their own, you can put all your other units in a second army. While the Barbarian, Knight and Sorceress faction will only be able to explore in one direction, playing as a Warlock allows you to have two armies defeating monsters and exploring in two directions.
The only problem with the single hydras stack strategy is that they are weak against other heroes that can cast spells, or carry a mix of melee and ranged units. But when the AI is starting to invade your territory on short maps, simply garrisoning the hydras in your castle is enough to discourage enemies heroes from attacking your castle. Then it's just a matter of getting the sulfur and ore to build the dragon tower with your second hero.
And the single hydras stack strategy can be carried in Heroes of Might and Magic II too because they only fixed the problem of AI swarming hydras in the third game.
Hydras. Learn to love them... until you get your dragons at least. And yes, the Warlock faction is totally broken in the first two games.
My usual tactic is to harass the enemy with flying until the minotaurs and hydras get in so the melee can do maximum amount of damage with barely any casualties. Also Gargoyles have good defense for a flyer so they're perfect harassers.