Essence of theBrimstone Witch

Pyromancy - a form of divination that involves using fire or flames to gain insight into the future or other hidden knowledge. It allows you to utilize fires to gather information.

Pyrophagia - the act of consuming or eating fire. It enables you to absorb flames from the environment for nourishment and healing. It has limitations and some things are harder to eat/swallow, than the others.

Pyrokinesis - the ability to conjure and manipulate flames, change their properties, and even command creatures of fire.

Fire Solidification - you can turn targeted fire into an unstable solid material, which can be affected by your pyrokinesis. At the same time, it's as hard as metal and as hot as real flames. You can decide how it interacts with other things.

Fiends - you can summon, create, or infuse items with fire spirits made from living things you've burnt down yourself, from their ashes, or by literally dragging specks of 'inner fire' from the corpses of your foes. They need to eat fire or highly flammable materials to survive, but even then have limited and usually short lifespans because they age over time. They are generally aligned with you, listen to your orders, and are loyal, but tend to be mischievous and 'fiery' in character due to their nature.

Source - you need some metaphorical source of flame around to fuel your magic. For example, you can use your own flaming rage or fires of will to produce the effects, which will make these two 'burn brighter,' but also turn to cold ash quicker. This means that if you use these two, your willpower and anger will suddenly be 'brighter,' but at some point, they burn out, leaving behind disinterest, apathy, or something similar. You will have to restore them afterward. So, it's better to use something like potential flames trapped inside gunpowder on your person.

Sourcing metaphorical flames requires creativity and thinking. Some things are easier and better than others to burn for your magic to work. For example, you cannot use the flames of another person's rage directly, but if you bait them into focusing their anger on you, it becomes easy to do. There are reasonable limitations to explore.

You are extremely talented at learning and inventing magical spells, brews, artifacts, and other similar things, as long as they are connected to or utilize flames as their theme - not only physical ones.

You need practice to learn new magic tricks. It involves a lot of trial and error, with each failure causing explosions, fires, and other collateral damage, usually drawing attention. You are 'fire,' which means better results are produced through action and passion - like gaining sudden insight about ideas you couldn't grasp before, especially in the heat of battle.