I have to admit I underestimated the damage a bit. I imagined it to be around 40 in most scenarios.
But I think streamlining the range wouldn't hurt. Instead of making it optional by expending exhaustion give it a longer base range and cause a fixed amount of exhaustion. Or perhaps make the user fall in a magical coma for X-time instead. Because I would say exhaustion rules are often ignored and I personally didn't even know how many levels there are and what they do.