Less forced of a combo than before, at least, but any situational use is overridden by the fact that every Vampiric creature essentially gains a permanent inverted version of Skyblitz for a lower cost. (instead of double damage to the opponent, double healing it dealt to you instead) Drain Life also becomes a much more effective bolt than Fire Bolt since Fire Bolt now has to contend with a bolt with 4 damage and +4 healing per 10 quanta as opposed to Fire Bolt's 3 damage per 10 quanta.
A set value is easier to balance than one that scales with other factors on the field. I recommend you have the ability be 'Gain X HP whenever you drain HP or quanta from the opponent.", as Darkness drains both HP and quanta.
I agree with Zbladder here. A set value would be better for this card.
Doubling would be OK in a spell version (since it only lasts 1 turn), but will likely be very OP in a permanent.
As far as being situational, I think its pretty good now on this front. It certainly has a wide applicability in a
mono and can easily be applied to duos using liquid shadow.
Once the bonus healing gets fixed, I think it should be pretty good... although as a shield I think it should have something like a 1 pt damage reduction as well.
