The problem I have with damage is that it seems to break the norm for what an attack is. Normally, a hit means meaningful contact, and a miss represents a lack of meaningful contact. Damage is dealt when you make meaningful contact. But here, either damage is being dealt without meaningful contact, or meaningful contact is being made on a miss. I assume the former.
While I'm fine with the abstract nature of hit points, damage still always has a component of injury to it, even when it's inconsequential. This is why poison and other addition effects on a hit work. Thus, I have a difficult time imagining a scene where a fighter does damage (meaning) without a hit (meaningful contact).
The comparison to Fireball is understandable but flawed. In 3.5 at least, fireball's save was listed as "Reflex half". A reflex save wasn't required to make the spell miss. It was required to mitigate the damage taken from the fire. Basically, do you drop prone in time? Compare that to Flaming Sphere, where a reflex save negates all damage, meaning you can actually dodge the sphere.
I get what they're going for with the Slayer theme, and I won't froth at the mouth about it, but I'd like to see a different approach.
