Galather's gnostic chain

Galather's gnostic chain was a wizard spell that was only useful against spellcasters. This spell was created by the adventurer Galather.

Effects
This spell took effect a minute after being cast, limiting the target spellcaster by only allowing them to cast spells equal in power to the last spell they cast before contacting the chain. The target was allowed to pick the spells they cast, but once those spells of equal power were exhausted they were required to memorize them again. The target was still able to use any magic items and scrolls in a normal fashion.

The chain appeared as a glowing spiral that hovered in the air above its targets before enveloping them. Invisible targets, or those protected by magical barriers, were not out of reach of the chain.

Dispel magic spells had no effect on the gnostic chain. Once held by the chain the target spellcaster had a very small chance of resisting the spell effects every several minutes. Their chances of success increased slightly with the passage of time.  

Components
In addition to verbal and somatic components, this spell required as material components three joined links of chain, a lock that had been used to confine a living creature, and a horseshoe nail to cast.