The opinion that Conflux "broke" the game (H3) seems pretty prevalent. They're ludicrously overpowered and I believe are banned from all tournaments. Why so powerful? Let's see:

1. Phoenixes. Mediocre level 7 units. Absurd speed and reincarnation are nice, but other than that, they don't really have much going for them. Oh, except maybe DOUBLE GROWTH. Seriously? How on earth was this seen as a good idea? I don't care what your strategy is, the odds of it prevailing against an army with twice as many lvl 7s as you are slim. This alone would be enough to make Conflux too powerful. But it's not the end.

2. Insane early game. Air Elementals are unbelievably powerful (because they were originally lvl 3, of course) and Pixies are pretty amazing also. Combine those with early spellcasting power (which basically all Flux heroes have) and you've got the unstoppable rush.

3. Magic. The Magic University essentially gives four levels to heroes without taking up any XP. That's ridiculous. They're all skills you want, too. Earth, Air and Water magic are all must-haves, and Fire has its uses. On top of that, most of their heroes start with Wisdom and a school specialization, as well as higher magic stats than any other town. Then, as if all that wasn't enough, their Grail building gives them EVERY SPELL (though, to be fair, with the gold and growth bonuses, Grail is a game-winner no matter what town it's in).

Basically their only weakness is level 5. Definitely level 5. Magma Elementals are incredibly underwhelming.

Now, I know why it's so unbalanced (the devs had a different town planned but the fans hated it so it was scrapped and Conflux was created on a very tight schedule, without proper time to balance it), but the question is, do you play with it? Do you allow it in games with your friends?

Seems fixable by making the units more expensive. Aren't there mods for that?

I don't play often for Conflux, only when I want a flawless victory.

And I believe someone has done a balance mod for Heroes 3, I think it was UndeadHalfOrc from Celestial Heavens, but don't quote me on that. Anyways, Conflux may be more balanced in that mod.

I always thought it was neat that their Grail building will give every single spell up to level 5 to everyone, even if you only have a level 1 Mage Guild.

As for the balancing, the units are already pretty expensive, and both flame/energy and earth/magma elementals are fairly mediocre for their level. However, they aren't nearly expensive ENOUGH, and they're still solid units. The big issue is the huge amount of health the air and water elementals have, and with the phoenixes. The problem I have with the phoenixes isn't their growth rate, honestly, it's the fact that they're obscenely fast and enable you to always cast spells first, even against things like azure dragons or archangels. Increasing costs for everything except pixies would alleviate a lot of the issues, I think.

Oh, and elementalists get one more primary stat point than other magic-based characters. I'm not sure that really counts, though, because all of the other magic characters were short one point compared to might characters anyway. But it's worth mentioning, I guess.

The WoG mod has halved Phoenix growth as option and as well offers the option to play with a kind of Rogue Town (units are taken from the Neutral ones like Thieves, Wervolves or Nomads) instead of Conflux.

Almost none of the troops being resurrectable (a game-winning spell) except for pixies and phoenixes negates a lot of conflux's power. With resurrection, or reanimate dead if playing undead or incorporating undead (with high morale items/leadership, it can be done), I can assemble pretty mediocre troops and still win, especially with expert earth magic skill, simply by resurrecting troops that are killed. That also gives me a huge efective boost in my economy, as I don't have to replace dead troops.

With conflux, almost anything that dies cannot be replaced except by waiting however many rounds for them to grow naturally from your town again.

I never use Conflux (except in random games where I have to take over one) and try to minimize the comp's ability to do so for the reasons you mentioned and the general spite I have for the town. I was hugely looking forward to the 'Forge' town (the cyber/Warhammer 40k type town that was originally developed before those idiots at the Astral Wizard site whined) and had to suffer the rushed, not well developed Conflux instead.

One of the great tragedies to occur in franchise PC game development.