Great job with this mod, and with changed files Matt.
Couple questions :
1) skill.txt is for defining parameters for lvling up skill
eng_skill.lng is for text description in hero screen in game
skills.lua is for skill mechanics right ? I aks because in AP/CW there some really weird things in skill.lua file, and i have no idea how to change how skill work in game. Changing eng_skill and skill.txt is no prob, but when i start game there are no some of changes i added in my files
2) Glory is it necessary to add every unit for -lds% ? Or is it possible to add strings form special_params.txt, example sp_lead_orc (all orcs listed in special_params.txt file), sp_lead_demon all demon units, etc. I like your idea for this skill, this way it`s useful during all game, not just in first 10 hero lvls so i wanted to add it to AP/CW.
3) what files i need to add in mod folder to get that unit in game ? I tried to add champion unit form adventure mod for AP to Red sands, but every way i try some errors report

. Is there any more files for units then this : champion.atom , champion.dds , champion.lua ?
4) i also wanted to add some new spells but got stuck after changing spells.txt. Idea was to make spells like hell breath, just to bonus poison dmg, and %chance for poisoning to help players against dragons/demons. What else i need to change ? i see in your spells all translated to eng which is great, but here are my problems - How to add new slot for spell in spell book (must i delete some existing , or will it add it self somehow ?

, Adding png files for spell in book, for scroll for shops, and for effect(poisoned during battle) anything else ? ,
spell_effect.lua , spells.lua , spells.txt , spells_common.lua , spells_hint , spells_power.lua do i have to changed all this files to add my spell or ...?
if you can give some advice thx in advance