I love creating magic systems, and I love helping other people develop their magic systems. I put together this list to help you brainstorm what you magic system can and can’t do.

1. Where does magic come from?
2. Does magic come from within?
3. Is magic a resource?
4. Can magic run out?
5. If it runs out does it naturally replinish?
6. What determines the strength of your magic?
7. What limits your magic?
8. Are there spells of various magnitude?
9. Does magic deplete a persons physical strength?
10. Is magic found inside living creatures/people?
11. Can you access the magic within other living things?
12. Is magic use verbal or written?
13. Are there time constraints for casting spells?
14. Does magic require sacrifice?
15. Who can perform magic in your world?
16. Does magic have to be learned?
17. Are people born with magic?
18. When do magical abilities manifest themselves?
19. Are there places to learn magic?
20. How long does a person spend at school learning magic?
21. Are there levels of magic users? Master, novice, journeymen?
22. Do magical abilities manifest differently in men and women?
23. Is magic an ancient tradition?
24. Has magic been lost and recently rediscovered? 
25. Did the gods give magic to mankind?
26. How did people come up with spells? Trial and Error?
27. Does magic require artifacts?
28. Can objects be given magic?
29. Does artifacts lose magical potency?
30. Can anyone use a magical artifact, or does it require a magic user?
31. Is magic inherently good or evil?
32. Do the people in your world fear/love/respect magic?
33. Are magic wielders paid for services?
34. Are magical people identifiable by a physical trait?
35. Does the government keep track of magic?
36. Does magic rule people?
37. Can you control people with magic?
38. Do people need to recharge before using magic?
39. Are there colors associated with magic?
40. Are there magical creatures?
41. Can magic be taken from someone?
42. Are magic users of a specific bloodline?
43. What benefits does magic give someone?
44. Are people changed by their use of magic? Physical strengthened, mental enlightenment?
45. Can magic be stored to use later?
46. Is magic transferable from person to person?
47. Is magic practiced differently throughout the world?
48. Does magic have a spiritual connection?
49. Is magic tied to the elements?
50. Are magical discoveries taking place?