To be honest, I think the hp gain and poison removal is enough.
adding supernova and draw a card seems a little too much of a big last chance, imagine having a miracle deck with this, and suddenly for the card drawn, you get miracle and boom, basically all health back, back in operation, yeah the chances are a little grim but still, if it is a total turn around of the game, its kind of slack imo.
but i like this idea, i reckon adding supernova only to upped version.