Wizards are Light and Dark. Sylvans Light and Destructive.

The 3 factions which have Summoning are Haven (with Light), Dungeon (with Destruction) and Necropolish (with Dark).


EDIT:
In my opinion roleplay/story-wise (not talking about balance-wise), Sylvan and Haven should have been swapped. Sylvans should have Light and Summoning, since they're more associated with Elementals and summoning in general (look at HoMM4 for example) and Humans should have Light and Destruction, since they don't seem to be averse to using destructive forces against demons/undead.

Also

Elven campaign level 2 seems to be the first one where I get my ass kicked. 3-4 weeks into the game a powerful hero comes and I can do absolutely nothing to stop him. Tried surrendering my Elven town to him and then rushing, but it didn't work out either.

Going to restart completely and this time try gonig to the sea instead of the underground. But having spent the full day on it, I'm not really happy...

If anyone has any tips on how to beat level 2 of Elf campaign (Hard difficulty) then I'm all ears.

If nothing works I'll try a reload from a previous level that will hopefully have a better random seed. If still nothing, I'll restart the whole campaign on *gulp* Normal (and there I was complaining about Normal being too easy...).

I never got that far, so I'm afraid I don't have anything for you. I had started the first Elf mission, but I didn't get to the point where enemies started attacking me before life interfered.

Does your main hero (Findlan?) have both Logistics and Enlightenment?

Yes.

What sort of hero is coming along? Has the story or cutscenes, such as they are, provided any possible clues on courses of action?

Nothing much storywise. Demon hero with lots of units. His appearance seems to be scripted, but his later actions not so much. He seems to prefer to attack, and gathers units but never leaves them. i.e. he will go stronger as time progress but you can't hope he leaves his units behind and you catch him off guard.

Online help seems to indicate you have to survive this battle, after which it becomes easier.

Could be just a little bad luck on my part. Maybe just being at the wrong place at the wrong time caused him to attack my city too soon.

Got it now.

The strong hero starts on an island with no boats. He will however summon boats and attack when given the opportunity. That's why in my previous run he attacked me so fast. The trick is not to give him that opportunity.

There is a shipyard next to one of his towns, and another one in a neutral territory. So eventually, he will get a boat somehow. However, fortunately the AI isn't smart enough to create a boat just for him to summon. The only way he can get a boat is if you are stupid enough to build one in your town and leave it unoccupied, or another of his heroes builds a boat for himself and then leaves it somewhere. Usually that hero attacks you, fails but his boat is left behind, for the strong hero to summon. That's what happened last game.

So the trick is to immediately occupy and empty boat.

I'm now at the stage where I got all other shipyards secured. In fact, all enemies are conquered except the ones on that boat-less island, including the strong one. But now I can go to them at my leisure.

And finished. 2 days before the new year end.

Next in line is Dark Messiah of Might and Magic, then HoMM V expansions. And I think I'll stop with Might and Magic universe after that, given how bad the series becomes.

Congrats!

Did you get through MM8? I don't recall your progress.

Oh yes. Finished it before starting HoMM4 (playing all in release order)