Ok so this is some good news, it seems like virtually all damage type spells do call ModifySpellDamage either directly or through AreaEffect (which seems to call MSD regardless of spell if I understand the syntax correctly?), including spells that dont have specialists like Titan's/Lightning, Destroy Undead and yes, Land mine (also Armageddon).
While all the enchantments, regardless of having a specialist or not get routed through SetSpellInfluence. And here only some have the hero bonus actually applied although I feel like you could probably hijack some of the existing cases by switch manipulation?
The code in SetSpellInfluence keeps referring to a "jumptable 00444701" with 49 cases but I cant see any table at that address?