Can I use black dragon scales from Magiclysm as armour material? If so how?
If they are defined in the mod’s material.json sure, otherwise you’ll have to add them as such
Even if i create the mutation, what will dictate its appearance?
The tileset you are using.
Does creating my own sprites, or modifying a pre-existing one need me to do something about tilesets?
Yes.
Looks_like for items will make them copy that item’s sprite. (I do not know if looks_like functions for mutations, check the docs)
- Is it possible to add mutations like Disease Immune or Infection Immune (also forgot their ids) in the "flag"s of other mutations?
Like how Mycus Fireproofing has “HEATIMMUNE” flag?
If they are flags, sure.