Well, this is a two card combo too by your parameters, since you need reliable healing or you will "deck out" once you are forced to use this too many times. Of course, that's damage, but the concept is the same, is it not?
Not really. Even if i play it without healing, you cannot counter it. Then i will die after some turns (or maybe i kill my opponent before), but you cannot counter it.
The "counterability" doesn't depend from the second card, like for Quintessence + Elite Charger and Eternity + Protect artifact.
Eternity alone = a direct counter exists (Quintessence or PC)
Elite charger alone = a direct counter exists (Lobotomizer or CC)
This card alone = no direct counter (of course there are indirect counters).
So, no, it's not a 2 cards combo.
Anyway, it's an opinion of mine, and these things are matter of personal tastes.