Can I use... UA/Third Party/Homebrew...

I try to be open to Unearthed Arcana, 3rd party, even the occasional homebrew. However, I also know from experience that opening this up can lead to lots and lots and lots of questions as players finally get the chance to test out their idea that won't be accepted into other games. This is where players can ask their questions, and I'll update this first post with the answers for others to see.

I reserve the right to continue to add, clarify, and on the rare occasion change rulings.


Published WotC Material
All of the books from the Player's Handbook to Mordenkainen's Tome of Foes and beyond is fine.

Unearthed Arcana
*Most Unearthed Arcana is fine. Exceptions include...

Modern Magic: Doesn't fit this Fantasy setting.
Gunsmith Archetype: Some Fantasy settings do well with guns, this one does not.

Third Party
Matthew Mercer's Blood Hunter is approved.
Princess class is approved:
Eidolist class is approved:

Third Party "improvements" to already existing WotC and UA material is not allowed.

Homebrew and Other Miscellaneous Questions
Can I change the damage type for certain spells to create a theme?
At this point I'm saying no. I know that fire somewhat dominates other elements as far as diversity and utility and some damage types such as Poison get little love. If this was a matter of one character asking me I'd probably be okay, but the thought of opening it to every character (which would only be fair) will take up too much time trying to keep track of and will take too much time away from the actual roleplaying.

Can I boost a race/class option that isn't as powerful?
No. I realize that some race/class options are overall more powerful than others, but that is part of the game.

Can I make a character that in-game is one race, but is mechanically another?
Probably not. It would take a pretty gripping reason that doesn't include either "I want to be mechanically stronger" nor requires a five-paragraph, convoluted explanation.