Experience, Gold, Runes, leadership, etc. variation

[KongMysen]

I just engaged fights against the Castle on Settera Today. The Samman Bounty.

I fought him twice since my demonololgist' cerberi finished the fight before I could ressurect my casualties. First go gave me around 9000 xp but the 2nd gave me 12000 xp.

I'm not sure why there's such a big difference between these two fights.

A few suggestions:
Summoned troops give xp? (Samman used Demon Portal)
Mana used by the enemy give xp?
Not loosing troops gives a bonus?

I'm guessing the Demon Portals, but I really can't see how those few portals can boost xp like this.
I think finding the correct mechanism require a lot of testing.

[DGDobrev]

1. Summoned troops - reading through the comprehensive russian guide, there is no mention that summoned creatures do not give XP: "The experience granted to the hero for a battle is directly related to the total Leadership of all killed creatures."

So they should give, because the XP in combat is equal to 1.7% of the total Leadership of all killed enemy troops (0.017 XP per point of leadership, as stated in the game files), before any XP modifiers kick in (learning, +XP items, medals, etc.).

However, that would mean that if you get a decent item (or do that in Zilgadis' boss fight) and leave a friendly gremlin tower alive, then you simply kill anything it spawns each turn, the XP may prove to be unlimited, provided you do a couple thousand turns. Very strange, as that can be exploited.
2. Mana used - no.
3. Not losing troops - no.

[KongMysen]

I guess it was the Demon Portals then..

I just think It was a lot of xp from those. He started with 60-70 Arch Demons, 1000 scoffer imps, Around 200 Demonesses and a hundred(ish) Demons..
I dont remember the excact numbers but each portal produced 3 Arch demons or 50 scoffer imps or smthing like that.
Fight ended at round 12, and he used armageddon twice and a mass-bless once, so he can only have used portals 9 times.

It simply cannot have been units worth 3000 xp. It just doesnt make any sence, even though I'm so inaccurate in my calculations