Draconic Armor

(Dragon Magic, page 16, DnD 3.5)

[Heritage]

You learn to block damage from successful attacks, lessening the blows with spell energy.

Prerequisite

Draconic Heritage, sorcerer le%"el 1st

Benefit

Whenever you cast an arcane spell, you gain damage reduction X/magic for 1 round (where X is equal to the level of the spell you just cast). For example, alter casting fireball, you would gain DR 3/magic for 1 round.