Exp gain system like in WoW

I want to make experience gain system like in World of Warcraft. Here's how it works: Hero gains no (or very little) exp for killing creeps with level at least 6 levels below level of killing Hero or 12 level above level of killing Hero. Have no idea how to do that, need help.

go to the game constants and change it for creep level....

That's not exactly what he needs.

Frankly, I'd trigger the whole thing. It won't be that sophisticated.

Decide how much experience a unit awards. Then, when a hero kills one, compare the hero's level and the unit's level. If unitlevel = herolevel, give the hero the full exp. If unitlevel = herolevel-1, something less, etc. etc. You'll probably want to award experience based on that ratio with a coefficient, so that you can just make a formula for experience awarding instead of making an if/then for every comparison.

I made a fully working WoW exp gain system and party system plus the exp works correctly when you are in a party
and parties are limit to 5 except for raid which is 10

Uh.. that's cool. It doesn't help any of us at all to boast, although it would help to share the script you used?

I might decide later to release it on wc3sear.ch as a spell and on here is the trigger section.

Alright, that would save a few people a lot of work. Thanks.