Quickleaf
Legend
It's an innovative idea. Reminds me of XGtE's chaos bolt, which determines its damage type based on the result of a d8, and if both d8s are the same, the spell jumps to another target.
However, this does make fireball feel like something that belongs in a wild mage's arsenal, rather than an evoker's or pyromancer's (who I would expect to have come degree of control over how big the blast is, e.g. with a check like @Helldritch suggests). If that's what you're aiming for, go for it!
However, this does make fireball feel like something that belongs in a wild mage's arsenal, rather than an evoker's or pyromancer's (who I would expect to have come degree of control over how big the blast is, e.g. with a check like @Helldritch suggests). If that's what you're aiming for, go for it!