Ya this has been reported, and definitely needs to be fixed. Those levels are technically reachable without adjusting the exp. Huge map, epic speed, over a thousand turns to grind exp, people could likely get there.

These extra classes would also fix this probloem in particular.

Maybe around level 20?

And yes, Sanati is right these levels can be reached. I for example have a level 45 sovereign on a huge map, epic progressing and i have run out of monsters, but can still grind Altar questmap, so technically i could level endlessly.

I'm curious, what experience was needed to go from 44 to 45?

The reason I am asking is because if you mod the game and then break it as a result of that mod, then that's a mod problem and not a problem with the basic game. So, is it reasonable that people will reach level 44 or 45 in an un-modded game?

Challenge accepted.

As there is a spell to level up a hero, one would imagine it is easy enough to get very high level heroes just by concentrating on mana production.

Unless I missed a patch note about it, you can cast Paragon as many times as you want so long as you're okay with a 10-15 hitpoint (don't remember the exact number) sovereign in exchange for a massively leveled champion. When you hit the minimum HP, you still cast it as normal, and don't lose any HP. Haven't checked to see if that's still true in LH though.

Why not just have a trait (or traits) that are repeatable or boostable that require all general and class traits to be learned and add a certain amount of certain stat/s each level up (you could choose which stat boost you'd want perhaps)?

There should be a repeatable option similar to the Epic Stat Boost option presented in D&D 3.5, if nothing else.

And yes, as parrotmath pointed out, though I did this by modding the core game, it is entirely feasible (if nearly banal) to do it within core game structure.

Maybe at lvl 25 or so, a general trait option that is repeatable should be a free Destiny's Gift?  Solves the problem.

It's insanely stupidly easy to fix this problem and a host of other UI issues: The player should be able to close the level up dialog without picking a trait.  Come back later and pick the trait you want.  Same with city level ups.  Same with picking champions.  There's absolutely no reason to do these dialogs the way Stardock insists on doing it.

It feels like I have been saying this forever, and I know it's never going to happen.  Stardock is in love with forcing the player to make a choice without sufficient information.  I have no idea why they're so fond of this mechanic, because it is absolutely terrible.  I have a sneaking suspicion that the first design document for this game starts like this:

1. Turn-based fantasy strategy with RPG elements

2. DIALOGS!  Anytime something happens the player should get at least two or three modal dialogs.  The smaller and less informative the better.

3. MOOOOORE DIALOGS!  If no dialogs have been displayed in a while, the game should display dialogs of random things.  Not sure what yet.  Maybe a picture of my dog.

4. ANNOYING DIALOGS!  In the case where a dialog would actually be a useful means of interacting with the user, make sure the dialog is as awkward as possible.  Throw in a lot of extraneous information (and of course, a huge block of flavor text), really just put whatever you want in there, as long as there's not enough information to make an informed decision.  And absolutely don't give the player an opportunity to close the dialog and return later, as they might try to use other means to find the information they need.

...

Hear Hear. I have complained about the city level up issue a number of times. I find incredibly annoying I can't look at my other cities when a city level up happens. On larger games especially I want to specialize my city and to do it properly I want to weigh what my other cities have. When I am choosing a building that might have an empire wide effect I want to LOOK AT MY EMPIRE and see what I might need. Not sure why it hasn't been changed, after a while I just got tired of complaining about it. 

Being able to dual class would be awesome, yes. And being able to look at the rest of your cities when a city levels up would be nice as well, with the random ass names cities get I can never remember what each one is going for.