Hello
Glad to still see ppl playing this great game.
First of : Enemy stacks labeling works in comparing total leadership worth of your and their army (if you lead 1 red dragon against 1 assassin, it will mark it as very weak 2500 lds>>100lds , but if you take 1 swordman vs same 1 assassin it will mark it as very hard since 35lds<<100lds. So you attack same enemy stack but depending of your army composition it changes difficulty level. And this system does not consider your items/skills/spells/rage in calculation, thus very hard enemy can be defeated easily using what you have at disposal.
Second : You took chaos/destruction too soon, and wasted runes lvling it early game. What does 50% more dmg mean to you when you dont have powerful spells, or high intellect for base dmg ? Early game you need in as much mana/intellect as possible to survive late to game when you`ll have Black hole/Death star and make 20K dmg per casting it. So that is already done, lets save what we can.
Change items in inventory at your disposal to get mana and/or intellect (drop anything +attack/rage etc you dont need it now). If you have some runes saved spend them on magic skill tree to get linguistics/thesis/concentration. At this point your strength isnt spell dmg, but spell control (trap, magic spring, stone skin ... and other spells that doesnt depend on hero intellect).
3) Units : drop guardsmen/sea dogs. Bears will be first line in attack/meat shields, snakes blitz dmg unit, beholder will do what they do best (evil beholders would be better), and take 1 (ONE) archmage to cast magic shield and move enemy units on traps (how are you doing on trapper medal ?), and out of way with telekinesis. Fifth unit take some controlling utility not mainly dmg choice (dryads would be perfect but to early in game for it). What was unit on Rusty anchor in tavern ? There usually players get some interesting picks from 4-5 lvl units early in game.
In end if you can post here save game file, i`ll look in to it, and get you some more ideas for what you have available.
Good luck