Fatigue, Gem Use, and Randomness?

[tinkthank]

I have watched a couple of battle replays to make sure, and I dont see how this is happening:

- An Air-5 mage casting Wrathful Skies with 3 gems (he had 3 in possession, used all) with 8 spell-casting encumbrance ended up with 61 fatigue.
- An Air-5 mage casting Wrathful Skies with 2 gems with 8 spell-casting encumbrance ended up with 60 fatigue.
- An Air-5 mage casting Wrathful Skies with 3 gems (he had 3 in possession, used all) with 8 spell-casting encumbrance ended up with 53 fatigue.
A shot of this Last one is included here. (His heroic ability is battle prowess (not reinvig).)

How can this be?

WC was the first spell cast, no summon storm power or anything. The mages were always accompanied by a SoS-carrier, but this one was always scripted to cast resist lightning first -- soothing songs etc. were cast later.

I was darn certain that Fatigue use (from manual) is 1/1+(CL-RL), so that a lvl-5 mage casting WC with two gems sould receive 66 fatigue plus the spell-casting encumbrance, so in this case: 84.
I was also certain that using extra gems gives you 1 more virtual level. So using 3 gems (instead of 2) should yield a fatigue of 50 + 8 = 58.

So is there a random element involved here?

[Chazar]

[*]Does the heat scale affect spell casting fatigue?[*]Does the magic scale affect spell casting fatigue?

[Vicious Love]

Chazar said:[*]Does the heat scale affect spell casting fatigue?

Only by raising encumbrance at heat-3 or cold-3.

[*]Does the magic scale affect spell casting fatigue?

Yep. That was my first guess.

[Kristoffer O]

Yes. Magic scale affects the fatigue.

[Endoperez]

Maybe the mages have different spellcasting (=base) encumberance?

[Tuidjy]

The variation you are seeing is definitely due to a positive magic dominion. As
far as I am concerned, the effects should be even more pronounced than they
already are. Ulm, for one, could definitely profit from spellcasting being much
harder in drain dominion.