I still think it sounds like a neutered Slay Living. Slay living Kills you, touch attack, 3d6 damage.
Harm does Not kill you, but puts you at 1d4, so yet another thing has to happen to kill you; waste of a spell, action, etc. It's a touch attack.
Destruction kills you. It's a *ranged* attack.
So we go from Touch, Die or Damage, Touch, d4 or Damage, Ranged Death or damage.
All you're making harm into is more damage on a failed save, and making that d4 there. I still think that with said modifications, it needs some Spice to it. Something that makes it more attractive then Slay living, other then the fact that it just does 3d6 more damage on a failed save.
The way you have it set up, it'd be no different then just Hightening Slay living. Infact, it'd almost be better, because Slay Living kills you, dead, no need for wasting a second action on you, cuz you dead.