All spells below level 4 are the same except for:
Summon Vine Ogre, 2x
Call of the Wild, .75x
Magic Duel, 5x (1 gem)
Wyvern, 5 gems (from 7)
Ice / Fire / Cave Drake, 7 gems (from 11)
Sea Serpent, 7 gems (from 11)
Devil, 8 slaves (from 7)


Level 5 spells have their cost doubled, except for:
Drain life, 4x
Invulnerability, 4x
Ice Devil, 3x
Hellbind Heart, 4x
Horde from Hell, 3x
Awaken Sleeper, 3x
Bane Lord, 3x
Thunder Ward, 3x
Fire Fend, 3x
Winter Ward, 3x
Storm, 3x
Faery Trod, 3x
Falling Fires, 3x
Falling Frost, 3x
Undead Horde, 3x


Level 6 spells have their cost quadrupled, except for:
False Horror, 6x and +1 level (air 2)
Relief, 5x
Wrathful skies, 6x
Enslave mind, 10x


Level 7+ are all 8x.


Construction:

Clam of pearls became 20W 5N
Fever Fetish became 10F 5N
Staff of Storms became 40 gems