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I tried combining a blank Air skillbook with Chain Lightning Scroll and i get invalid combination?
chain Lightning is a two point source skill therefore you will need a higher quality blank air book
Those are both elemental books. You either combine it with phys-based skills or non-elemental magic like necromancy.
yo is there a summon spider???
Summon Bone Widow is a normal Necromancer skill.
Bone spider. Necro spell.