Unofficial Content Policy
I think there's a lot of really cool Unearthed Arcana, third-party and homebrew stuff out there! I enjoy reading it, playing with it and thinking of ways to implement the occasional piece into my games and settings. I also like Eberron's philosophy of "if it's in D&D, it has a place here", and don't mind working with players to incorporate new and/or unusual options into most things that I run. That said, I prefer to work with content that I can be reasonably confident is well-designed.
If you want to use unofficial content of any sort (aside from anything I have already said is explicitly allowed for your game), please discuss it with me first. I'll want to read it over for myself, and if possible get an idea of how balanced and appropriate it is. While I can't guarantee that I'll accept any particular thing, I am more likely to look favorably upon content produced by well-known publishers or homebrewers (e.g., Kobold Press, Walrock Homebrew, Sterling Vermin Adventuring Company, etc.) or content that I can see has been well-received by the community with a lot of playtesting and feedback. If you can also provide a link to some evidence of this sort of playtesting and feedback, it may help your case.
I will generally request that you use the most recent version of whatever content it is you're interested in, including preferring published versions of UA content if they exist (e.g., if you want to use the War Magic wizard subclass, I'd generally rather you use the Xanathar's version than the UA version). If your content receives an update during the course of the game, I'll likely ask you to adjust your character to use the new version, but we can absolutely discuss it first, especially if the changes are significant and would affect the function or your enjoyment of your character.
I reserve the right to make changes to any unofficial content used in our game if it turns out that something is unbalanced or unfun. If I or anyone else in the party feels that something isn't working out, we'll probably take some time to discuss what's going on and how we can improve it. (This includes making changes in your favor! If you're feeling a little disappointed in how something is working out for you, let me know and we can adjust it to make it more fun!)
See Allowed Sources for unofficial content that is pre-approved for most campaigns, as well as for information on what's permitted in general.