Hmmm… Dicebreaker has the right idea here. You’d think Hasbro would be all over this with their Kre-O stuff. https://youtube.com/watch?v=4PM-BNztQx0&feature=share
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Hasbro did have D&D-branded Kre-O in 2014, but it was more its own game than it was to give the player customization options. https://kreo.fandom.com/wiki/Dungeons_%26_Dragons
(Note: I know the apprentice doesn’t sweep in and do the saving, but most people don’t know the name “Yen Sid.” I’m sure you got what I meant.)
I might need to build out my warlock (I have a 20th level warlock who can, Gandalf- or Sorcerer’s Apprentice-style, sweep in and save my sons when they’re being spanked way too hard during a game). I typically present him as Disney’s version of Merlin (yes, complete with Archimedes), so it shouldn’t be too complex…