ToME: the Tales of Maj'Eyal

Higher difficulty levels certainly deliver a satisfying level of challenge, and I wouldn't want to change that in general. But I think there are certain instances where talents or perks are disproportionately shut down by difficulty scaling, and in these specific instances it can disable entire classes that depend on those talents for their play style. I would recommend situational patches that make these talents or perks at least moderately useful at higher difficulties.

Stealth and charmed creatures should scale less severely with difficulty level than they do now. These are central features of their respective classes, and the scaling leads to them just being unable to use their basic functions on higher difficulties.

Charmed creature scaling seems to be inconsistent. For instance, Doomed's shades scale with difficulty level, actually making them fun to play in insane and madness, even if not necessarily too powerful. On the other hand, some classes that are centrally reliant on their charmed creatures, such as alchemists and summoners, do not benefit from difficulty level scaling. I would suggest making charmed creatures consistently scale with difficulty level. Madness is still hard if your alchemist's golem scales with it, for example, but at least it would be a playable challenge.

Stealth likewise just breaks on even moderate difficulties. Since it is so central to the flavor of rogues, it is a pity. I would recommend that See Invis/See Hidden not scale with difficulty level, or that Stealth be given an explicit boost depending on difficulty.

Stealth is actually pretty ok even on Insane. Its good at letting you get the first hit in and shadowstrike means that your first hit will hurt a lot. It won't protect you by making enemies overlook you, it'll protect you by letting you kill your enemies in a few turns.