Weird Arcana - Familiar's Shadow (New Spell)

I always wanted to create familiar-specific spells to increase the versatility of this class feature (and to simulate some legends about these magical creatures).

FAMILIAR’S SHADOW

School transmutation

Level sorcerer/wizard 4*, witch 4

Casting Time 1 minute
Components V, S, F (the wizard’s familiar)
Range personal (must touch your familiar)
Target you
Duration 10 min./level (D) (see text)
Saving Throw none; Spell Resistance no
This spell enables you to fuse your body with your familiar’s shadow. While in this form you can see and hear normally but you are effectively trapped inside the shadow of your magical servant. You can’t use any spell-like or supernatural ability. You can communicate telepathically with your familiar or whisper very softly (base Perception DC 15) to anyone touching or holding your familiar. Your spellcasting abilities are limited to touch spells of the enchantment and transmutation school without any components. The spell’s target must be touching/holding your familiar (or be touched by it). All these spells have their DCs increased by +1.

While in this limited shadow form your body is treated as if under the effect of the gaseous form spell. You are considered adjacent to your familiar for combat purposes. If you or your familiar suffer any damage, you must succeed on a Fort save (DC 20) or the spell is ended.
A familiar under this spell projects the shadow of its master, which can be detected by astute observers (base Perception DC 25).

Familiar’s shadow can’t be perceived by detect magic.
*In Pathfinder only wizards can acquire a familiar.