BlivetWidget
Explorer
If they kept the damage as-is but also included the potential for an injury, whatever that ends up being, it'd probably be worth 7th level.
That's what I was thinking. Maybe the injury one should be the regular one. Either that, or up the damage on the regular and make the rare one deal d10's
Admittedly we don't know what "injuries" are at this point, but I the concern I would have with using injuries to balance spells is the implication that it's a long-lasting effect. Such effects tend to wildly affect the potency of a spell depending on who uses them and on whom, which makes them extremely difficult to balance.
For example, Feeblemind is simultaneously one of the most dangerous spells for an NPC to use against a PC wizard, while being quite middling for a PC to use against an NPC wizard. The asymmetry in consequence means that as frightening as this spell is, I've never seen a PC bother with it, and for good reason.