Protection from chaos was an abjuration spell that created an aura around the target that shielded against mental and physical attacks by chaotic creatures. This spell was not reversible, but a counterpart called protection from law was known.
The newer version of this spell functioned exactly like protection from evil except the bonuses and benefits applied to attacks from the minions of chaos. The older version of this spell treated summoned creatures slightly differently; they specifically had to be chaotic in alignment, so this version of the spell did not protect against all summoned and extraplanar creatures, just the chaotic ones.
For the newest version of the spell, in addition to verbal and somatic components, the caster had to draw a 3 ft (91 cm) circle around the recipient using powdered silver. For the older version, the caster needed a small ring of gold or lead that had been tempered by a chaotic smith.