Quote Originally Posted by sithlordnergal View Post
But isn't there a literal in-game Boon from the DMG that grants an additional 9th level spell slot? Wouldn't that satisfy your condition for it being in-game and not meta-game since you consider rerolling a d20 to be an in-gams thing and not a meta-game thing?

I mean, its not exactly the slippery slope you're making it out to be. Though if a player were to ask to roll a d30 instead of a d20...I might allow it for a single roll provided they have a physical d30 on them. XD If only because that would be a very interesting dice to see.
I never said slippery slope, I just said I would not allow it. Boons are a variant rule that I have never used. If a player wished for a boon, I would allow it, but which boon would have to be consistent with the PC's deity.

A one time use of a d30 is a crappy wish and a waste of a 9th level slot and a further waste of a spell that the PC may lose forever (33%).

I guess you just miss my point entirely that a wish in the game should not be a wish in real life. But if you're willing to give your car to a player that wishes for it, that is your issue.