Probably the PCs who spring into action right after being healed above zero HP, effectively telling the enemies, "I'm back! Feel free to knock me down again!"
1d4 damage? It's pretty hard to put a price on the ability to snap someone with a rubber band and be miles away from the scene of the crime.
Unless that price is $49.99 on Amazon. Then it's a bit much.
It sounds like this might be past the interesting complexity threshold where you can no longer calculate the problem, and must instead feel the problem. When you choose 3 difficulty, does it feel better than 4 difficulty?
I'd love an RPG to run with feels, but I'd still have trouble doing it...
4th level players? Oh god, no. Give it to their characters, though. That would be fun. Except you might blow the players' minds a bit with the whole A-Hit-Is-Definitely-Meat thing. One way to avoid that and reduce the Vorpal power is to make the hit that reduces to zero HP the one that lops...
Speaking of minor changes...
A little change goes a long way. That's why I encourage GMs to take control of all their lists: spells, skills, monsters, classes, etc. It's your game, GMs. Don't let a game designer change it without your approval!
I'm a fan of the exit-interview method too: ask what the outcome was, knowing what the rules have to say about it.
The 50% rule sounds good for getting things moving, but it's too close to the succeed/fail dichotomy for me.
I mean, I guess you could call the GM an "indifferent and sometimes...
. . . for the PCs. Funny that 5e doesn't seem to have a Flee action for the DM to use. I wonder why.
Doesn't this just reduce the odds of a Flee result, sort of like giving a bonus to the save vs. panic on a d20? I mean, someone could insist that the bonus should have a bell-curve...
That's one of the other quantum outcomes. When you try to pin its location, you lose certainty.
It's one reason. Another reason is that larger groups are harder to hide.
Web is sort of like the WTC towers. There has to be something to hold up the vertical dimension of the webs/floors. If your chandelier anchor falls, or your core structural beams just cease to exist, then so does the spell/building.