Various heroes build advice?

[satomz]

It could be due to you not getting as much experience from mobs. I think at lower level areas, the level of mobs tend to be higher for their actual difficulty, thus making experience gain faster. I'm not sure which area you are adventuring in right now, but it could be that areas you tend to be in when you first hit level 20 (e.g. Kourna) might be inefficient experiment-wise. Don't take my word for it though, since it's just a guess.

If you want to focus level up your heroes to 20, I recommend doing quests since they give you set amount of exp no matter your level. You could also bring the hero along on a mission or primary quest if your party composition and mission requirements allows for it.

[satenia]

even though my W/Mo is level 20 it seems my heroes that are under level 20 do not level up for some reason. is this because the amount of exp i gain from level 20 mobs is so little?

anyone have any tips or tricks ?

The last few levels can go quite slow. Make sure you have the heroes below 20 in team when accepting quest rewards, as these usually give a decent amount of XP. It's also an easy way to level the ones you don't use that much.

[BrettM]

Heroes gain experience from a kill based on their own level, not yours, just as another player in your party would gain XP based on his level. If your team kills a level 20 opponent and your heroes are level 15, their XP gain will be calculated based on a level 15 character killing a level 20 opponent.

If you want to speed up the process, you can use scrolls to boost the XP gain from kills. These will work on heroes, though they do not work on pets.

[Shen Al Cahar]

Not sure if this is off any help to the OP, but if you want to lvl the heroes you got after completing nf, the best way to lvl em is just do Gate Of Madness HM (one of the easiest and most fun mission in the game imho). Lvl18 heroes will be lvl20 by the time you reach Shiro.