Inferno tactics.

Regarding a specific tactic for Inferno, the suggestion was to build Ifrits right away and use them. The uncertainty lies in this. These are level 6 units, and they are built one after another; you can't build them like Bog Wiverns. Hence, the conclusion: it's not always advisable to rely on Ifrits. And what if you're on a small map? Or one with scarce resources? If, for example, you're playing as a Castle or a Rampart, the tactic might involve building archers and clearing the territory with this small army, which ensures the capture of mines and resources with minimal losses. In Inferno, archers are weak, and you can only clear areas without losses using Ifrits, as has been observed. But to build them, you need different resources and five levels of creatures built, besides hounds, I think.
There are no strong heroes, the hero's average range is also small, and the terrain they traverse (lava) is usually very small in area on the surface, but larger underground. (I'm talking about the random map generator, 200%). Often, this Castle is also located underground, which means that development also becomes more difficult.
In general, there can't be a specific tactic. It's a Castle that is very dependent on the conditions.

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One more advantage that hasn't been mentioned is that you often get a portal and an explosion in the School of Magic.

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Is there no special tactic for Inferno?
In the first week, focus on getting Ifrits; in the early stages, they can fight well due to their immunity to ranged attacks.
If you somehow manage to get a Book of Fire or a scroll with Armageddon, then Ifrits become a very serious asset.
The expendable hounds and especially the Imps are generally a whirlwind against melee units.
That's the tactic.

It's unlikely that immunity to ranged attacks is important in the early stages. The main thing is to capture resources. And battles with heroes are the result of an unplanned encounter. When I play, I don't even expect to encounter anyone in the first week. Even if it's a small map, the hero collects what he can with a small force, while the troops stay in the Castle and wait for the enemy; the first building is a Stronghold. But that's already a difficult situation. In general, it's an interesting topic to discuss playing on an S map.