I`m not for overall change, but some slight combination.
Expl : all classes have (almost) same medals, why ? Make different class different playthrough, i personally in every game get pet to 60+lvl, and rage medal to max lvl. Change medal advancement so getting some medal unlock other choices then after those you get other etc . . .
Change spell effects as in how they depend to item and some hero skills (not just order/diss/chaos skill lvl`s).
As i said on my previous post unit exp unlocking talents, something like orcs adrenaline. Now ppl kite islands get dragons and from first battle have strongest units in game, with my idea you`ll have to win some battles to get units to be usefull.
New items, but no totally new, just upgrade already existing to be useful later in game (i did this to couple in red sands and it interesting to think new item ideas).
AND PLS SOME KIND OF MULTIPLAYER.
Playing against AI is interestng just up to some point, but after trying couple army/skill builds AI just isnt enough for testing our tactics
