Make this a non-shield permanent, it's not so strong that it needs to be mutually exclusive with other shields. I've thought of designing a card like this myself, though people had already so I didn't. I was going to call it "Contingency."
I don't see it making much sense as an Entropy card either, though - Entropy is all about chaos, not knowing what to expect... this card seems more in line with Aether, but of course Aether doesn't need any more stall cards. Perhaps make it Time - since Time could use a little help on the stability end of things. Sure, Time already has Procrastination, Sundial, and Rewind/Eternity, but none of those really shut the enemy down, they just delay things a bit, so it has to also think about rushing in just about any situation. Wouldn't hurt to give Time one more delay to hide behind. It's like a Sundial that can be played before it's needed, which is faithful to Time's heavy emphasis on planning and setup.
Oh, and drop the cost a lot... Sundial does about the same thing, gives a chance at an extra draw, and for only 1 quantum or even free. This card should cost 2 at most...
One last minor technicality to add: your card text says when "health falls below 0" - this means if health reaches exactly 0, the player isn't rescued, which I doubt you intended. It should say "reaches 0." No need to add "below 0" to that either, since the display ingame never goes to -5 or whatever.
