Personally I don't see too much of a use in a T4 healing nova and could even be detremental to the game.
Firstly this upgrade doesn't differ too much from healing nova and isn't all that unique except the anti-anti-heal effect it has.
Secondly having the anti-anti-heal effect is really strong for just an extra 1.6k souls not account for the extra healing it provides too. You are basically making a healing item that cannot be countered in any way and that is not very fun; imo the only item that shouldn't be countered is unstoppable and that's it.
Maybe instead it would be cool to have a healing nova that also doubles as a mini-decay so for 1.6k it can provide offensive capabilities too.