In our homebrew universe, we don't have resurrection (as we feel it cheapens character death, etc. - don't really want to get into that debate). Spells like revivify, raise dead, and resurrection simply aren't on anyone's spell lists. They don't exist.
But then Xanathar's Guide to Everything includes the Path of the Zealot barbarian (p. 11), which has the class feature Warrior of the Gods, which is all about resurrection:
At 3rd level, your soul is marked for endless battle. If a spell, such as raise dead, has the sole effect of restoring you to life (but not undeath), the caster doesn’t need material components to cast the spell on you.
In a universe without resurrection, this class is now missing a key feature. I want to come up with something to replace it that is still balanced and has a similar flavour but that doesn't involve resurrection.
I've come up with this:
At 3rd level, your soul is marked for endless battle. If you drop to 0 hit points, you have advantage on death saving throws, and any creature that attacks you in melee whilst you are at 0 hit points must roll a natural 20 on their attack roll to score a critical hit against you; otherwise, the melee attack is considered a normal hit, and you only suffer one death saving throw failure.
Compared to the original feature, is my proposed modification of the feature balanced?