Basically transmutation takes alteration's buffs and turns them into permanent effects. All stats could be buffed only to 30 at tops, with few exceptions (e.g MR 20, HP 60...). The amount of stat-buffs' strength depends upon mage's magic power, in relevance to the cast spell.
MP | STAT INCREASE
1 = 1
2 = 2
4 = 3
6 = 4
8+ = 5
So if you cast Mind's Eye with a A5 mage, the mage gets 3 to perception skill.
1-3 levels of this school is about stat boosting. From level 4 you start to get permanent ability-gaining spells. These may seem expensive, but there's a reason for that. In construction you may get some of these abilities cheaper, BUT you lose precious equipment slots.
Transmutation spell list:
I'll put only one example for each level. The descriptions of the spells are very brief, only to show, what this school is all about.
Lvl 0
Mind's Eye (A1 / 10 air gems) = increases perception by 1-5.
Lvl 1
Power Surge (F2 / 10 fire gems) = increases attack skill by 1-5.
Lvl 2
Jthull's Manifestation (N4 / 8 nature gems) = increases HP by 10.
Lvl 3
Equilibrium of Planes (S3 / 20 astral gems) = increases magic resistance by 1-5.
Lvl 4
Bestial Fury (N3 / 25 nature gems) = gives berserker +3.
Lvl 5
Binding Agony (D2 / 5 death gems) = gives 1-3 random afflictions to a mage in target province.
Lvl 6
Mystic Illusis (S3 / 3 astral gems) gives ethreal to three random units in target province.
Lvl 7
Ghostly Wings (A3 D1/ 15 air gems) gives the ability to fly.
Lvl 8
Natural Swiftness (3W 1N / 15 water gems) doubles the movement and gives 1 to map walk. [[affects only once per mage]]
Lvl 9
Elemental Augury (F2 W2 A2 H1 / 15 astral gems) gives protection from all elements.
The fearful question: what do you think of this?