The idea of having to take a character down below negative their hit-point total to kill them starts to get problematic once they get past the first couple of levels; a mid- to high-level character pretty much needs have no fear of death from a one-shot unless it's an attack that's doing hundreds of points of damage. Add to that the use of Hero Points to guarantee successful Death Saves, and a PC with more than 30hp or so is pretty much unkillable.... unless.....
Intelligent creatures will be aware of the issue, and if they spend a bit of effort after the PC has gone down whacking away at them to make sure of automatic Death Save failures, then the unconscious PC is in real trouble. This is where being swarmed by vicious little bastards like goblins or kobolds gets very dangerous.
Note: I believe, during play-testing, death was set at negative CON+Level; I'm not sure why they decided on the current system. I suppose to give players as much opportunity as possible to save their characters.I've previously made my disdain for the new Find Familiar spell known. What a stinker.
Another spell that is giving me pause is Lesser Restoration. This is a real uber-spell. It requires no material component, and it pretty much gives the PC four spells for the price of one 2nd level spell slot: it replaces the old Cure Disease, Neutralize Poison, Cure Deafness/Blindness, and Remove Paralysis. That seems amazingly powerful for a humble second-level spell to me.
I think that what I will do with it is, first, make it a lengthy ritual spell, and second, give it a reasonably rare and expensive material component that varies depending on what it is that the caster wants to heal. That still leaves it a very powerful spell to have in one's repertoire without letting it become overly dominant.
Lesser Restoration2nd level abjuration
Casting Time: 3+1d4 hours (ritual)
Components: V,S,M (50gp worth of powdered gemstone, which is consumed by casting the spell — diamond to cure a disease, amethyst to neutralize a poison, aquamarine to cure deafness or blindness, or emerald to remove paralysis.)
You draw a magical circle of runes and sigils around a creature and, after a period of 4 -7 hours of chanting and magical jibber-jabber, can end either one disease or one condition afflicting it. The condition can be blinded, deafened, paralysed, or poisoned.
I think that should do the trick. At least it will make it a bit less egregious.