Hero Leveling

I was just wondering if anyone knew how hero's are affected by power leveling?
Obviously you can just quest them to 20 but i would rather power level them to 20 or just level them by solo farming. Also how close do they have to be to get the xp?
Thanks in advance.

Heroes need to be within your agro circle to get XP. To level them go on Wurm runs in NF, collect quest rewards with them in the party, run missions with low-level Heroes...whatever. It doesn't take long.

Can you do trolls?

Keep hero near zone as you kill them. When they're about to die use your mission maps to flag hero behind zone (back into droks). This will cause hero to spawn right next to you and get the exp as the trolls die. Just be careful not to zone your hero too early.

I Generaly find simply normal questing, along with swaping them out when recieving rewards, works fine.

I believe they are effected by bounties in NF as well.

Thanks those are all good ideas.

Its just an example of the above but I found Vizunah Sq to be good (only ever played foreign qrt though)

Levelled 2-3 levels on Olias on a single run with full party