First of all if Nightshroud stole significant amounts of health (let's set it at 4), then something like owlbeast would've likely been a lot more reliable and powerful. It is simply win more and does little at parity or when at a disadvantage.
Trying to combo it with Death Knell is a different situation but still feels too slow with an unreliable impact compared to just triggering bond with Trinity Wings, playing spells, and buffing your new board with owl.
As for the body a variety of things can deal with it. Since you spent 4 mana on shroud they likely still have an arcanyst and can play Trinity Wings and ping it for 2 damage. A spent celebrant could trade with it. Cassyva could ping it with her BBS, Vanar could flash freeze it or use an illusion on it. A random 2 drop could trade into it. It is vulnerable to alchemist. Even worse, the negligible heal could've done nothing to prevent lethal.