Custom Classes and handling them in your campeign
I'm an "experienced" player but am relatively new to the DM role. As a player, I have a tendency to work with my DM to make semi-drastic changes to the standard classes/spells so that my character can play the way that I want it to. My DM's are usually fairly comfortable with this homebrewing, and in one of my current playgroups, I am actually playing a completely custom class that I created with the help of other members of my playgroup. As we have played, the custom class has undergone more than 1 or 2 minor and even major changes to try and better balance it with the other published (or at least Unearthed Arcana) material. My DM has worked all of these changes into his campaign and now has another player using another completely homebrewed class (similar to Mat Mercer's Gunslinger Fighter Subclass) joining our group.
So, my question is: What are your thoughts on allowing players to make substantial changes to an existing class or even playing as a completely custom class and how do you go about making sure they are balanced with the published material?
It is my personal opinion that a new homebrew class, race, spell, etc, should be balanced to the best that it can be with existing content and fulfill a gap in the existing content, whether this is mechanically, flavorfully, or both.
If anyone is curious, my own custom class has been a slow work in progress for about a year now. Originally it began as a small project to satisfy my desire for a more demonic-oriented D&D class, and eventually it turned into this:
It's been play-tested a bit (mostly the Shadow Origin, as that's what I play) throughout this time by myself and friends, but I know it is not perfect. I would very much appreciate any comments, constructive criticisms, and feedback anyone may have for this as well if you have the time. I also welcome anyone to playtest this as they will. I'm very interested to see what others think of this class and other custom classes/spells/content as a whole in regards to 5th Edition D&D.