Soulfire

Soulfire is the ability to use the soul to enhance magic, affiliated with heaven. The Fallen Angels refer to it as the fire of creation, and it is the antithesis of Hellfire.

Description
Soulfire consumes part of the user's soul to enhance his magic. The soul regenerates over time, or through acts which are "good for the soul", but will kill the user if it is completely drained.

Soulfire gives structure to magic; it could theoretically allow a path to be made into deeper Faerie by stabilising the gateway. While |angels use it, it is unknown if they use it on its own or bound to a form of magic.

Despite being similar to Hellfire in enhancing magic, there is a key difference: Hellfire gives power to the means; Soulfire gives power to the intention, giving the user much finer control on the spell.

Small Favor
In Small Favor, Harry Dresden is granted Soulfire from the archangel Uriel, after he has lost Hellfire, when Lash was erased from his mind at the end of White Night. Soulfire manifests as a silvery ghost of Dresden's force spell, and a blue-white supercharged version of his fire blast.

Bob informs Dresden that Soulfire is powered by one's soul. Given time, the soul can regenerate, unless it is used all up. If the soul is exhausted, however, consequences are not pleasant.

Turn Coat
In Turn Coat, Harry Dresden uses it to boost his Sanctum invocation and to strengthen the garrote he used on Shagnasty the Naagloshii.

Changes
In Changes, Harry Dresden uses it to create very realistic animated illusions of his companions to a greater detail than before.

Cold Days
In Cold Days, Harry Dresden understands that soulfire is fueled from the user's entire being - not only from the 'soul' but the amalgamation of what makes the Self (a product of every decision made, every thought we have, every action done), and that it is the user's entire being and identity that fuels it.