Note: This spell first appeared in the Hellbound: The Blood War boxed set, and were designed for fiendish spellcasters. DMs must give specific permission for PCs to have access to these lower-planar dweomers.
Fostered protection can be cast only on creatures that already possess some level of natural magic resistance. Other beings simply aren't affected by the spell. Also, this spell does not affect magical resistance granted by magical items or other outside sources.
When cast on a magic-resistant creature, fostered protection increases the resistance by 2% per level of the caster for the duration of the spell. Under no circumstances can the target creature's magic resistance exceed 95%.
The material component for this spell is a drop of blood from a magic-resistant creature (not the caster's or the subject's own blood).
Notes: Rare for planar priests; otherwise, virtually unknown.