I'd move Slow to spell level 3-4 and/or also increase its cost, if that's possible.
I would bring back cartographers, but only so they don't open the whole map, but rather a radius like a watchtower at some point on the map chosen by the player or randomly (some treasure zone).
Generally, when I stumbled upon a Heroes stream on the internet a couple of years ago, I was pleasantly surprised that the game is still alive and tournaments are being held for it. Then I watched a HotA stream; a lot was unclear to me, there were massive changes compared to the classic, although it seemed like the same thing + expansions.
Ultimately, it's easier for new players to get started with SoD, especially those aged 30+, who once played specifically on this version, and then smoothly transition into HotA and others.
I haven't played WT, but I like the idea of moving Fireball to fire and DD to water; that would balance the elements.
But it wouldn't be the SoD everyone is used to anymore :smile27: