The 'Consecrate Spell' feat from Book of Exalted Deeds adds the [Good] descriptor to spells cast. Is there another way to achieve this for arcane spellcasters, e.g. as a prestige class feature?
The reason I'm asking is the 'Spell Focus: Good' (also from Book of Exalted Deeds), which is the only (non-greater) Spell Focus feat that gives +2 to DC. Having a cheap way of adding [good] has obvious benefits in the combination.
For energy, there is the energy substitution feat from Complete Mage, but what is there for [good]?