It is not real spellbook design, but I find this idea cool and wanted to share.
With Warlord, there will be many new Earth spells. I can't wait to see them all and create Labirynth-like spellbook. Not sure yet, if it will be Warlord's or Wizard's build (but I'm biased toward Wizard).
The main concept will be around Wall of Stones and other walls, limiting movement and LoS of every creature. This will create an adventage for heavy meele fighters like Bloodcrag Minotaur, Earth Elemental or Iron Golem.
In case of flyiers, there is Gravikor. If you play Wizard, you could place it so Huginn will be out of range and can cast Teleport on you or your oponent for even further movement controll.
Walls also create nice environment for traps and simmilar spells.
Idea is purely based on theme rather than gameplay reasons, but I plan to give it a try.