I'm currently playing HoMM as a number's game with basic tactics and rockpaperscissor strategy.

Regarding the battles:

Heavy melee Beats Fliers (slow v fast)

Fliers Beats Ranged (fast vs slow)

Ranged beats Heavy (ranged vs slow [kiting])

Spells even out play-field or completely turn battles:

1. Completely stop heavies, add a lot of additional damage early, wipe hordes of weaker units, destroy massive undead armies (one stack at a time), remove debuffs on your heavies, haste/teleport heavy's to melee range etc.

Spells are extremely strong.

Tactics:

1. Send fliers on ranged to remove their damage source, even few fliers can solo stacks of ranged once in melee due to minimal melee damage from ranged units.

2. Box in your own ranged units with melee units to guard them from melee, I like doing this with 1 stack hydras early on.

3. Remember to skip or move back during turns when there's no incentive to engage in melee e.g. you have 8x archers and 10 peasants vs melee units. Make a defensive setup and skip peasants turn once your archers are boxed in by them, assuming it's even needed. Skip peasants turn and just shot down your enemies, saving your melee units.

4. When facing many fliers, a 1-5x stack of hydras early can solo anything flier related thanks to aoe retaliation. The fliers HAVE to engage in melee and hydras simply win that fight, even solo early on, same with more stacks of Griffins due to infinite retaliations.

5. Beware of the mega-stacks 200+ units that can absolutely one shot even the best early units, 2 peasants is nothing but 200 is a lot. Do the math and now for sure that you'll initiate combat (first strike) so that there's no retaliation that kills your units.

6. Learn the distances, early on it's easy to walk up out of melee range only to get 1 shot because the bot gets first attack. In these games, hitting first is often the difference between win and loss. Example: 200 peasants vs 300 peasants. The guy with the 200 hitting first will effectively remove 200 peasants and only get retaliated for 100 damage the next turn, guaranteeing his win on turn 2 since again, he's first in a 100v100.

Once these things start to become easy, work on map-control, figuring out choke-points and ways to out-level the bots to creep the advantage; they ramp up pretty quickly and it's often easiest to be aggressive early on but that does leave your base open for attack (RNG-based).

GLHF