Harmful necromancy is cast at one level lower. Fire spells are enhanced on the noonday layer and diminished on the night layer. Other elemental spells may be enhanced or weakened by the terrain. Spell keys might be available to reach off-plane sources of information, but other uses seem improbable. Wizardly spell keys are natural objects.
Alterations require blown leaves.
Conjuration-Summonings require a bit of food that the animal will like. Divinations are in silver ore. Enchantments and charms require quartz crystals. Cloud-evocations require a treebranch struck by lightning. Necromancy requires a bone.