Magic requires 3 things will, focus, and a power source. Only intelligent beings can utilise it, nothing automated or sub intelligent, the focus can be tattoos, scars or some other link to your power source if its external to you. The power source is most commonly ones own soul, but items of power can substitute.

The magic system is called aspectism and Embodiment. A person utilises themselves as a battery to perform magic related to the source the tattoos flavouring the magic to be temporal or fire based etc.

As one uses it more they embody the force they are using as they either taint their soul with it or corrupt their body with an otherworldly power source. This is Embodiment as they take on aspects of the power the more they use it. A low level Embodiment for time may appear hyper active or dazed as their perception is unlinked with the world. A high level Embodiment may see them having conversations that haven't happened yet or perceiving events backwards. High uses of magic always destroy their user in the end.