Here’s what I did -don’t worry if it doesn’t make much sense to you even after reading the initial articles, it should do once you read the stories (implying I’ll finish them… 😉 )
*Strength: depending on the magician and the spell; isn’t a “do it all”.
*Prevalence: Only Shadow World creatures have a form or other of magic
For magicians: spells [words] are used to give focus to the energy the magic user chanels through them; words can be merely thought or even just the intention given when the spell is simple and/or well-known
For creatures: the magic is tied to their element plus the ability to hide their true form.
*Power: is dependant on the type of creature; for magicians it depends on the type of spells learnt. Ultimately, magicians could know about all types of magic but it’d take years. They usually pick either a branch [combat-defense-healing-nature] or useful -to them- spells.
* Magical Interaction (with itself and people with it): some spells can block/cancel others, there isn’t a “cancel all” one; within Shadow World magic is normal, outside it’s unknown
*Magical Items: it’s possible to ground a spell with a material item or to tie a spell to a material item. The duration depends of the magician and the amount of energy chanelled into it
*Randomness: a spell can fail or be less strong than intended if magic user is already tired/not concentrated
*Sourcing: natural energy within and without; a spell can exhaust someone
*Range: again depends of spell and magician, usually a few meters