[Fatt_Shade]

Not 100% true ckdamascus.

Most likely what "level" the rage skill is (so usually the ones that need more rage points).

In Ap/Cw best exp rage skill was lightning ball, and it cost much less then dragon dive/astral spirits/lava call. So rage spend/exp gained is a bit tricky.
I`m not sure who made it, but there was pet.atom file in 1 of Ap mods , with list of all pet dragon skills, lvlups and dmg/rest/exp gain. Great file to have fun with in moding rage skills.

@Aleksandar777
Here look in game folder/sessions/addon/data.kfs/pet.atom Open that file with notepad and look for rage skills like this :

  olaf_wall {
    hinthead=pet_olaf_wall_name
    class=scripted
    script_calccells=olaf_wall_calccells
    script_highlight=olaf_wall_highlight
    script_attack=olaf_wall_attack
    attack_cursor=attack
    place=2
    level=3
    default=level1
    upgrade {
    // âńĺ ďŕđŕěĺňđű čäóň ďîńëĺ /
      // health                 őčňű ńňĺíű
      // defense                çŕůčňŕ ńňĺíű
      // push                   âîçâđŕůŕĺěűé ńňĺíîé óđîí, %
      // rage                   đŕńőîä ˙đîńňč
      // rest                   îňäűő
      // exp                    îďűň ęîëüöŕ
      level1=level:0/health:150,defense:10,push:10,rage:6,rest:2,exp:6,level:1,def:0,cn:0
      level2=level:1/health:250,rage:+2,exp:+2,level:2
      level3=level:2/health:500,rage:+3,exp:+2,level:3
      level4=level:3/health:1000,rage:+4,rest:+1,exp:+3,level:4
      level5=level:4,LV:>9/health:2000,rage:+5,rest:+1,exp:+3,level:5
      level6=level:5,LV:>14/health:5000,rage:+6,rest:+1,exp:+3,level:6
      def1=level:>0,def:0/defense:+10,push:+10,rage:+4,exp:+3,def:1
      def2=level:>1,def:1,LV:>7/defense:+10,push:+10,rage:+4,exp:+3,def:2
    def3=level:>2,def:2,LV:>11/defense:+10,push:+10,rage:+4,rest:+1,exp:+3,def:3
    def4=level:>3,def:3,LV:>15/defense:+10,push:+10,rage:+4,rest:+1,exp:+3,def:4
      contr1=level:>0,cn:0,rage:>30,rest:>3/rage:-10,rest:-10,cn:1
    }

There is all info for wall rage skill upgrades per lvlup. Expl : for 5th lvl of wall, you need 9th lvl of rage skills

level5=level:4,LV:>9/health:2000,rage:+5,rest:+1,exp:+3,level:5

and on that lvl your wall will have 2000hp , cost 20 rage , rest 4 , and 16 exp gain. Consider that this is multiply with enemy/all total leadership ration in moment you cast rage skill (enemy army have 5 stacks of 100 peasants , and you have 1 troll = 5x100x5lds / 1x1100lds = 2500/1100=2,36 so if you use wall rage skill in that moment you`ll get 2,36x16 = 38 rage exp).
Expl 2 : for same wall skill, to upgrade defense to 3rd lvl , you`ll need

def3=level:>2,def:2,LV:>11/defense:+10,push:+10,rage:+4,rest:+1,exp:+3,def:3

wall of at least 2nd lvl level:>2 , and rage skills on 11lvl LV:>11 . So to upgrade wall defense takes higher rage skills lvl then to upgrade it to 5 lvl basic with low defense.
In end if you wonder how much any rage skill gives you exp per use , try to figure out what did you upgrade for it so far and in that file calculate it`s basic exp gain. Anything you get is outside of battle. In battle that amount is multiply with lds ration at moment of using rage skill (so if you get in battle with 5 stacks of 10000 lds, and enemy have total army strength of 1000 lds - very weak, dont use much rage, it`s waste of time for skill animations. Maybe just for gold skill, rest will give you almost nothing).

That`s all i know on rage exp, for more ask something specific, i`ll try to help.
Have fun