UnitAura

[Satrina]

Current version:

name, rank, icon, count, debuffType, duration, expirationTime, unitCaster, isStealable = UnitAura("unit", index or ["name", "rank"][, "filter"])

Awesome new version:

name, rank, icon, spellID, count, debuffType, duration, expirationTime, unitCaster, isStealable = UnitAura("unit", index or ["name", "rank"][, "filter"])

spellID - exactly what you think it'd be