Hello. I want to say my opinion. Maybe someone sayed something like this before, but anyway. If u read this - thank you. And sorry for engrish.
1. First, i think there must be less random in hero lvlup. Maybe there schould be some non-random mechanic behind that. Something like - 1 trait is basic trait(thing everybody have acess too), 1 trait - magic school, 1 - trait that u can lvlup(things like Potential II, Vital Strike III, 1 - class specific trait(defender I-administrator I, Impulsive, Invoker - etc.), and 1 random(which can be rare classed with some luck). But which one trait u get, u dont know, and still this will make heroes more buildable and straightforward. Also, improve system behind trait clasification(common-rare) - these things is just priority. For example common have 5 priority and rare - 1. And this will determine how often u will have chance to get those. Overall system that i describe is very simillar to one of M. and M. Heroes 5.
2. Second is blood traits. They are not uniformd. Actually one of the best blood trait is gilden, yea this is basis that is good for blood mechanic. We get 1 early game bost(30 mdef), 1 ongoing boost(+hp), and 1 tradeoff(+50 manacost). I think every blood trait must have this line.
Altar actually is good too, because it gives something all-around usefull. An because 10% exp is not much, it have no tradeoff.
I think Tarth one is bad. It give only early game boost. I think this bonus must not be lost if army is larger, just reduced by -50%(this will make bonus ongoing, +1int is good all the time). Also i think there must be heroes-only bow specialization(maybe simple +2 initiative to any tarth hero with bow), because bow on heroes are not so usefull, it is not a big one. Maybe tarthans must have some encumbarance feature, something like +1int if light, -1 if other status.
Pariden one is ok, and unique. But +1 to spell mastery or Mdef - is meh. Just incresease this number.
Kraxis is not so good trait. Just maybe make it ongoing? something like(plus to current bonus) +15-20% to basic armor when bellow 50%(doesnt count enduring and autodefend).
Quendar one seems bad at first glance. But it is very helpfull in some situations. But this makes this trait VERY situational. There is 2 ways to improve this, maybe some firebasic feature(+10% to weapon attack with fire source?), or play arround elitism(if unit\hero is above average level in battle, he get something. Even +2initiative will be good).
Wraith one is terrible right now. Too huge drawback, too weak bonus. It doesnt scale. Maybe instead of simple +3 for kill, make it +2xlevel, or even just change to vampire like(heal unit for 5-10% of damage done).
Trog(offtop: like concept of trog, but features of faction are bad right now. i see them as giants, not as bland berserkers) - very good ongoing bonus. But early game lacking. Simple +1-2 to attack will good to flav, and make it very usefull.
Capitar and Umber - just useless. It is bad, because we got alot of heroes based on this race, but i dont know what to do here. Capitar maybe can have some upkeep reduce bonus(this unit cost -50% less to keep?). And umber, while good concept, get small bonus.
3. Third - is combination of 1 and 2. What if game will have new type of prestige traits? They are unique, but interesting choices, that reauire alot of prerequisites.
For example, what if Magnar(race, not faction) hero chosed path of the mage, and have fire magic? Actually magnar get some relations with fire, why not give this guy opportunity to pick up "Fire lord" trai, that simple gives 25-50% bonus damage to fire spells?
Another example. Kraxis are good diplomats. Why not to give governor hero opportunity to pick up "Charismatic" tree. Charismatic I: +0.25 dimplomatic capital +0.5 prestige, Charismatic II: +0.50 diplo, +10% percived trades, Charismatic III: +0.75 diplo, +0.5 prestige, +10 percived trades. Actually i feel this bonus very strong. Why not to allow this trait only from 10 level? Seems interesting(imho) and balanced(at least balancable).
Or something else? Lets take gilden defender hero. Gilden are perfectly magic resistant. Lets add this trait - if this hero maxed out "spell defense" tree, give him oppotunity to pick up trait that will give him +25-50% protection from ice,fire,lighting damage. Seems strong, yea. But hero will be very antimagic specialized, because it requires alot of levels, and give nothing more than magic protection.
Why add bonuses only to 1 type of hero? Lets visit gilden again. They got that antimagic theme, so why not to add to assassin or warrior(or both) trait that will add +1 physical damage to attack per magic school of his foe? I mean, if your gilden antimage will attack some enemy hero that get Death V and Fire III, attack will get bonus 8 damage during this attack.
Also why not to add some gamebreaking late game abilities? Lets see at tarth. I think they are good assassins. Why if this assassin maxed out vital strike(not simply) and have impulsive(rare trait) - he get "Ambush trait". This trait simple gurantees that first 2-4 attacks in battle of this hero will be crits. It just synergies both impulsive concept and vital strike concept.
It seems very good to improve bloodline trait like that. Wraith Defender - regulary useless choice. But what if add him some "Soul Collector"(or whatever they do with slained enemies, dont know flav) trait. even tree. Collector I: +100% to heal from blood trait, Collector II: every time hero is healed by that trait he gets +25% to defense for 1-2 turns, Collector III: heal works every time enemy dies(that heal doesnt trigger Collector I and II).
Lol, we even can make every hero with traits like that. Wraiths everyone can be based on this. Just Warrior gets attack instead of defense bonus, Mage dont incresease the heal power, instead he gets mana equal to healing done.
Why one trait per hero? Lets check gilden again. Governor this time. First trait "mechanic" - gives +2 initiative to golems and catapults. Why not? Master craftsmans they are. Second trait - smelter, +1 iron per turn. Yea boring one, but still making differrence in game, because only gilden heroes can generate iron this way.
And almost every combination is easy too create some trait. Kraxix warior? They like spear, give him spear mastery trait(+attack+initiative+armor penetration). Pariden Governor? Why not make him able to generate mana. Or is he defender? I can imagine even 2 traits, Earth afinnity(doubles bonus of earth shards), or Water affinity. Damn even if he is assassin, we still get air affinity. Bored of afinnity? Okay, lets do that, Pariden mage can have "Wisdom" trait, that makes him able to cast every spell(even if dont have school) heroes in hism army can cast. Seems imbalnced? Ok, make prerequisite 2 archemage traits. Bored of pariden?
And we can even make some bad choices very good. Who will use gilden mage? And if get "Lifebringer" tree? If he have life magic and healer he will be offered to pick this. I: +50% to heal magic and makes cost of spell non affected by blood, II: +100% to heal and halves upkeep on regeneration. Well, who will use him now?
Even if not all heroes will have this prestige traits, maybe 2-3 traits per race - still will make heroes managment alot more interesting.
4. This one is simple. There is too much map generation in magic effectivity. I mean, i want to use fire. But get every shard, and not fire. I even have fire archmage, but still cant use fire effective. I suggest "*element* Speciality" trait tree. It is short(3 levels maybe), requires a archamage of this elemnt trait, and it simple gives this hero(only to him) virtual shards. So if u have Fire Speciality II, 1 fire shard on control, and cast a fireball with that hero, his spell will count not 1 shard that u have, but 3 shard, +1 per level of speciality.
Yea it seems powerfull, but to balance it out Speciality disable to pickup other schools, and Other schools disable speciality. So if u want have pure Air\Fire\etc. mage - u cand do that.
Thats all. Thanks for patience.