 If you liked
Toaru Majutsu no Index
|
 ...then you might like
Sousou no Frieren
|
This recommendation encompasses the entirety of the Toaru Universe (ie; Railgun, Accelerator, ITEM, etc). Both media perfectly illustrates the unique applications of power & magic within its unique power systems; that is also blended with a unique world that has their own deep history which enhances their world building.
The intricacies of the supernatural/magical abilities gets delved-in deeply and yet maintains coherence that grounds our understanding. Furthermore, their applications can cohesively work together with other character's abilities as well which adds such originality and cleverness to the overall storytelling.