- "We don't have the energy, but it's not that we need to generate it, because somebody already has it. We just need them, and they can give us inexhaustible, unimaginable power."
"That's no one."
"That's the Source. That's the place it all comes from, how people used to get shit done when they needed a fucking miracle. The divine."
- —Richard Corrigan, Kady Orloff-Diaz, and Julia Wicker[src]
Deities, more commonly referred to as gods, are beings of immense magical power who operate on a level far above most magicians and magical creatures. The Old Gods are the primordial entities that are responsible for the creation of the universe, magic, life and reality itself, as well as the 'parents' of the modern deities of mythology. Alice stated that to the modern gods of myth, humans are like toys, but to the Old Gods, they're like cells in a body.
The gods are known to be the creators of many worlds in virtually all of the Multiverse. Children of beings known as the Old Gods, they hold immense power that is possibly surpassed only by the Wellspring, the source of magic itself. They are a very ancient race that play a role in shaping the history of Earth as evidence of them appearing in myths. It appears that they can take an active part in human lives and affairs however, most choose not to.
Deities come in many forms, as diverse as the humans who worship them. Those seen thus far appear to possess a physical form. However, Reynard the Fox has also shown the capability of possessing the bodies of others and work through them, while only briefly showing his true bestial self. He was also able to briefly take the form of his mother to trick hedge witches.
The gods are characterized by their immense durability, knowledge and advanced magical ability. They appear to be virtually immortal and can only be killed by extreme means such as by other gods and powerful magic. The power and complexity of magic a deity can perform appear to be nearly limitless being capable things such as flipping planets over and creating and destroying entire worlds with little effort. Umber, with no assistance, was capable of creating a Cuba|pocket world of his own design.
Gods like magical creatures possess an innate source of magic within them that is not connected to the Wellspring and typically doesn’t run out. Despite this, a god's power can be depleted when a deity gives their entire being into a creation such as Prometheus and Julia Wicker with the Seven Golden Keys. Even if a god loses their power they still retain their immortality and virtual invulnerability.
Gods can conceive with mortal beings, their offspring are known as demigods and possess great powers. One such demigod was said to possess "more magic coming off him than every Magician on Earth combined".
Gods possess a "god seed" within them which can be transferred to mortals. Without it, they are left powerless and without magic save for their immortality. A human turned deity can grow this seed through acts of virtue such as answering prayers, performing miracles and granting favors. A human given the seed can become a full god or goddess if they grow it to completion. The conversion of Reynard's seed within Julia implies that the seed of a born god is also affected by the virtue of their deeds.
The biological essence of a deity, acquired through sex or simply being given by the deity, has a tremendous affect on magicians. Consuming or otherwise having a gods essence within a magician imbues them with power greater than a Master Magician, mentioned by Bigby to be almost god-like. This allows them to touch objects of immense power, such as the enchanted Leo Blade and the key to the Wellspring, and cast spells of devastating magnitude. The essence also grants the magician temporary immortality, allowing them to resurrect themselves after being killed.
The effects of the boost wear off after an unspecified amount of time. It should be stated that the discrepancy between the boost can be quite large depending on the magicians use of magic. Alice's boost from Ember lasted for a few days while Julia's boost from Reynard the Fox lasted for significantly longer due to Julia refraining from casting spells whereas Alice was actively training with high-level spells.