[Nagot Gick Fel]

Originally posted by spirokeat:
Some spells cost well in excess of 100 fatigue....Am i correct in assuming they are supposed to be cast by a mage who is then not to be performing anything else ?

Not necessarily. A level X mage can spend up to X extra gems beyond the spell requirement (or up to 7, whichever is lower - at least in special cases).

The first extra gem is used to raise the mage's level by 1 - and as as side effect, it will reduce his fatigue. The remainder is also used to reduce fatigue, just as if the mage was 1 level higher per extra gem spent in the spell, except extra levels beyond the first only count wrt fatigue reduction (not spell # of effects, range, magic penetration, etc.). So don't expect a level 4 mage to cast a spell as efficiently as a level 6 one thru extra gems only.

Example - a level 4 mage wants to cast a level 5 spell that costs 5 gems and 500 fatigue. He can use up to 4 extra gems, one to raise his level to 5, the remainder to reduce his fatigue to 500 * 1 / (8 - 5 + 1) = 125. That's not factoring in the province's magic scale modifier and the mage's spellcasting encumberance.

That's the theory. In practice spellcasters tend to be somewhat conservative with their gems, and may not use more than 1 or 2 extra, as long as they start with less than 70 fatigue and end with less than 200.

and does the communion/sabbath have a share effect for fatigue ?

Yes. There was a detailed thread on this topic a week ago, you should give it a look.