I'm not sure I got this one's effect. How does this work precisely?
Why the decay mechanic? I see it as a futile coding complication. The vampiric attack should be just fine, IMO. Maybe lower the attack by 1 further point. And reduce HP so that they fit the card's cost.
The unupped is currently better than the upped. Since half of 0 is 0 it actually doesn't take any damage from decay without something pumping its attack.
Or maybe the cards' to match the tables'. If the card is supposed to be whats in the tables than I think its slightly more balanced but I'm still not sure.