Nailara was written to make certain themes, genres, and stories easier to tell. Many times, 5e has rulings that are excellent for high fantasy, combat laden adventures - but can sometimes fall short when trying to depict other stories.
The following are some personal rulings, interpretations, and homebrew that I commonly use, to align better with the setting. When able, I will also add the justification or lore reasons why it is this way, in italics.
Keep in mind, that not all magical effects that exist in my setting are represented with the existing 5e spells. Just because I say something is not possible with a certain spell does not necessarily mean it is impossible to accomplish.
Lore
Firearms exist, but are rare
Firearms were actually invented quite a while ago, and have been reinvented many times. They have not been widely adopted or researched further due to the existence of magic. Few nations are interested in developing firearms - they require refined resources, supply lines, and expertise to operate. Instead, they could train a mage who simply needs food and rest to be a far more lethal threat.
Evolution
Evolution exists as a concept, but many creatures originated from divine intervention, or their adaptations were accelerated because of magical mutation. Additionally, due to the presence of magic and gods, some evolutionary adaptations can start popping up even when natural evolution is halted (for example, when a species becomes intelligent enough that physical adaptations become less necessary for survival).
Feywild
The material plane and the feywild are effectively the same place in this setting. The material plane is massive, with uncountable star systems. It is also the home of Qamara, an Ancient. The great forest where she lives is magical and unpredictable. There are portals, and the terrain folds and stretches in strange ways. There are many other fey planes that intersect with the material plane, and with the Great Forest. The majority of stories and themes about fey still stand strong in this setting - it's just also a place you could walk into, if you really wanted.
Spells
Teleport must be to a destination on the same planet
In Nailara, the material plane is unique because it is incredibly and seemingly infinitely vast. Other planes are much, much smaller. Mages find spells easier to invent and cast when they are specific, and making a spell that can travel to anywhere in the universe is very very difficult.
Modify memory interactions with Memory Stones
Modify memory targets the memory in a creature, not a stone. It is much more difficult to modify a stone's contents than it is to modify a creature's.
Zone of Truth works more like Sleep
Simply put, I hate Zone of Truth. I like mysteries and subterfuge, and drama. Zone of Truth can extremely easily remove those elements, because it is full of absolutes, and the caster knows exactly what situation they are in.
