Posts from Skills for an Inferno hero.

I won't speak for everyone, but personally, when I play against demons and develop light magic, I always take fire resistance. This not only negates the effect of the Fire Lord but also provides -50% damage from fire attacks, so it offers good protection against hellfire. Demons always have hellfire, regardless of their magic, so fire resistance is simply essential when playing against a demon (if you are developing light magic, of course).

I don't really consider hellfire to be some mega-powerful skill that a demon must necessarily enhance, and opponents must necessarily develop protection against it. In Lords of Chaos, they weakened its base damage but increased the spell multiplier, and in practice, it turns out that the damage is weaker than it used to be. In my opinion, Cursed Sign with Devil's Strike is much better now. Withering Flame requires level 4, while Devil's Strike only requires level 2+, and attack is still much more useful for a demon than chaos magic, in my opinion.

I don't really consider Hellfire to be some super-powerful ability that a demon absolutely must enhance, and opponents absolutely must invest in protection against it.

If the demon has Withering Flame, the effect of abilities is canceled.

Not exactly. Withering Flame increases the damage of Hellfire by 50%, so if the damage was previously 100%, it becomes 150%. Fire resistance reduces the damage dealt by the fire element by half, so 150% divided by 2 equals 75%. Therefore, if a hero has fire resistance, and a demon has Hellfire and Withering Flame, then when Hellfire activates, the unit will only receive 75% damage; without Withering Flame, it would be 50%.

I'm not arguing about fire resistance; it's a useful skill against demons, and you explained it well. I'm just wondering if Withering Flame is really that necessary, even though Hellfire is almost always taken. Spending 4 levels to enhance a skill that isn't very strong right now seems wrong to me. Light will counter Hellfire, Fireball from Pit Lords, the Fire Lord's skill, and it will also protect against dark magic if a demon goes that route, so it's very questionable to go with Chaos.

Storm Lord is indeed a weak ability, but Ice Lord is quite good. As I mentioned above, it's enough to take the basic Chaos abilities and one of the lords, and that's it. You can ignore the rest. The exception is if you're playing as Groll, then you can take Blazing Wrath or something else.

I repeat, there is no need to upgrade Chaos beyond the basic level. The core spells will be Ice Bolt and Ring. The difference between Chaos Expert and the basic level is only 24 damage in these spells. Therefore, we take the basic Chaos – Lord of Cold. The basic level is also sufficient for learning Cold Steel. If fire spells are available instead of ice spells, then we take the basic Chaos – Lord of Fire. Nothing else is needed. In my opinion, Magic Depletion is not worthwhile for demons, as it requires level 4. It is easier to take the basic Defense – Reflection, if you need to protect yourself from magic (and it is even better to take Marbas as your hero right away, as he is an anti-magic hero and already has Reflection) + Defense has many other very useful skills, and Defense itself is a mega skill for demons and not only. Advanced Chaos makes sense to upgrade only if you are afraid of enemy machines (Deadly Cold) or if you are playing as Groll (he already has Advanced Chaos).

In practice, on small maps, spells of levels 4-5 are usually not learned, and instead, Ice Bolt and Ring of Ice are used.

Why is it not easy? In a month, you can accumulate enough resources to build all the guilds (although this is usually done towards the end of the construction).
Dark Magic is strong, I agree, but it can be dispelled, and it deals minor damage.
And why do you think that the Inferno army is not the best? In my opinion, it is on par with the human army and ranks among the best.