Tactics and strategy in Heroes of Might and Magic V.

NECROPOLIS. Hero leveling.
Regarding magic, we are subtly offered (judging by the guild of mages) – summoning and darkness... Both are very effective, but it's not worth taking them together, because you won't be able to cast everything anyway... It's no secret that the Necropolis army is durable, but it lacks healing... With the magic of darkness, you can make the opponent's army the same (but much smaller), plus various "small things" like berserk... Summoning is for more experienced players... Arcane Shield and Phoenix will not hurt anyone, but elementals... With a ring, the "fire wars" perk, and expert magic, many of them will be summoned, and in a trained necromancer army, they will be a significant asset... And, of course, raising the dead, which allows you to save your army... You can also take Enchantment with summoning magic, because it doesn't have any fast spells... Defense is a must, attack too – the army is numerous but weak, attack will help skeletons, zombies, and souls deal good damage... And there remains luck/learning to choose from... Learning will help you match the Knight/Elf in stats, and luck is never superfluous and will help against mages... I advise you to take a perk that grants mass stone skin...
And... regarding dark energy, I don't think it's worth talking about whether you need to spend it all... We give preference to vampires/zombies...
NECROPOLIS. Army.
Skeletons. At the beginning, it is worth making them archers to clear the map, gradually turning them into warriors... As soon as you can gather all 7 stacks, you can safely turn archers into warriors... Skeletons, together with zombies, can неплохо protect liches (if necessary, you can add souls), and the enemy will have to face a direct attack from the liches... If you have luck, skeletons can неплохо handle removing retaliation... A large shield will protect liches from archers... If you quickly capture a dwelling at the start and constantly engage in converting, you can gather a decent number of skeletons, which can be used to remove retaliation from particularly tough neutrals (losing 10-30 skeletons), and then attack with all your might without fear of losses... With good map control, you will have 3-5 tier 1 creature dwellings, and these are skeletons... Ideally, you should not lose anyone after the third week in medium battles (30-40 djinn, for example), except for skeletons – these can be considered expendable...
Zombies. These cute creatures will hardly help until the endgame, except to cover the liches... (if you have to fight neutrals with zombies, you attacked too early, and the losses will be significant) Therefore, their number should grow continuously (dwellings, converting, necromancy)... But in the endgame... 600/700 zombies are simply unstoppable, the opponent will not spend their action points on them (and if they do, your army is free just because of them)... The tactic of fighting with zombies in the endgame is as straightforward as a bayonet – just go to the archers, trying to hit as many troops as possible (because you removed their retaliation, right?). Regarding the upgrade, it's not very important, I always take the second one (so they are more durable)...
Souls. Just like skeletons, they are used to remove retaliation, because they can be missed, and more than once... In principle, in a battle with tier 5+ neutrals, they should be in the front, and then dragons/rippers should come (to the poor neutrals who spent their retaliation on missing the souls or were stunned by the skeletons)... With good defense + stone skin, it is very difficult to kill a soul, but you will lose 1-2 in medium battles (this is normal)... The counter for souls is any mage (I said you shouldn't touch them, right?), so if for some reason you attack casters, don't take souls into the battle, they should die from physical damage...
Vampires. These are the shock troops of necromancers and one of the best units in the game, with good control, you can gather about 60 vampires in a month, and their ability to vampirism (it sounds silly) allows you not to lose them at all... Vampires are not retaliated against (did you take the second upgrade?), so their task on the battlefield is to attack the strongest stack or vulnerable archers/casters... Never attack a weak stack with a vampire that they will kill, it is better to weaken a strong stack, and the weak stack will be dealt with by heralds/dragons (exception – the weak stack's turn is close, and it can reach vulnerable targets)... With skillful combat, vampires can take all the hits and then immediately replenish them... Remember – vampires are shock troops and the main force of the necropolis, give them preference in everything (including strengthening them with magic)...


Added 1 minute ago

I don't think so...

Yes, that's right :)

So what are you waiting for? You know, you are just talking – in some things, I am wrong – excellent, write what, I will try to convince you or agree with you... If you don't need it, someone else does....