I was thinking about making a few new spells for 5th ed D&D. Are there any official guidelines on how to go about doing so? If so where is the information found? Please note: I am interested only in 5th ed, no other edition's materials.
In reading through the question How can I let my PCs create new spells in a balanced and fair way? various advice is given but not about the mechanics around the development of the spell itself from the DM's and game design perspective.
The reason why I say that the question does not answer my question is because damage is covered, but not range nor spell shape specifically. Casting time is covered but the information seems a bit disjointed. And not everything is about damage, either. There's nothing in any of the answers concerning how long non damaging spells should last (or take to cast). Also nothing about how to determine if new spells should require concentration or not