Tested 1.5.3, right off the bat a suggestion for updating the "Resistance" skill: in addition to reducing SP in terms of damage dealt by destructive spells, make it decrease the area of effect of the opponent's mass spells. For example: with Expert Fire, the area of Berserk is 19 tiles. Let it be that with Advanced Resistance, this area becomes like with Advanced Berserk - 7 tiles. With Expert Resistance - Expert Berserk becomes Basic. Mass Slow with Resistance - not on all units, but on some area depending on the Resistance level, etc. The numbers can of course be tweaked further.
In this case, Resistance would actually have a decent form. What it is now, personally I don't like, it's worse than it was. The words of a boy not, but an old WT player who came up with a bunch of innovations.
There is no goal to make Resistance a must-have skill and the sole and main counter to all magic. The game already has other ways to counter magic, and new ones will appear. But deliberately taking Resistance at, say, level 10-15, already knowing that the opponent is leveling a mage, now makes more sense and (more importantly) has a smaller variance in usefulness. Found some boots on top of that and boom, almost 50% reduction already. Yes, this is not a tool against Mass Slow and Berserk. But no one said that one skill should counter absolutely everything.
So removing isn't enough, you need to trim the edge, another way? Why?
The main atmospheric strangeness is - why does progression suddenly stop? For all specialists in creatures and spells it continues continuously, but for skills it suddenly stops at level 20? Why the hell, asks level 50 Sandro from the campaign? And if we're going to limit everyone, then why exactly at level 20? What's so sacred about this level that skeletons stop gaining stats and Chain Lightning damage stops increasing? From the outside it looks like some random nonsense pulled out of thin air.
Well, the second point - is there really certainty that 100% skill enhancement at level 20 is even normal? Let's say, if you make the growth of all specializations 3-4% per level without a cap, then 100% would only be reached at levels 25-33, and you rarely get much higher online, no matter how long you drag it out, the map will end. A 60-80% bonus at level 20 is still noticeable, but not as crazy as 100%.