The vamp drain is okay. And, I definitely agree that it works well thematically and makes this card unique since there is no mass drain effect available yet. I was mainly concerned that the the damage was too high.
Dealing 8 is much better than 15. Its still very high, but at least some things will be able to survive after being buffed.
I think the unupped one should probably deal slightly lower damage (maybe 7 or 6?) in this case since creatures are generally weaker and there will be fewer buffs to help things survive in the unupgraded meta.
As for upgraded creatures. This is a tricky topic. Generally speaking, bypassing immaterial is something of a taboo. The status needs to be respected in terms of the value it adds to a card.
More specifically, all immaterial creatures have been balance wrt cost to account for their high level of protection. This additional cost needs to be respected when considering the balance of a card that can bypass the status.
For example: SoW bypasses immaterial status and the benefit to doing so is that it adds an additional effect.
Likewise if a negative effect bypasses immaterial status, there should be some kind of penalty for doing so.
You have some options there, although space is limited. Some examples:
-Do less damage to immaterial creatures (they tend to be low HP naturally)
-Remove or invert the drain for immaterial targets
-Give the owner of the immaterial target something in exchange...(e.g. return dead card to hand, give new cards, more hps ... etc.)
I'll nerf the Unnupped to 6 damage, it makes sense after all, I might make the upped cost 15 even, because the upgrade would be for extra damage, not for cheaper cost (There's a major difference between 6-8 damage than their is from 15-12 cost.)
I wasn't thinking, so much, that this card itself would damage immortals, I was trying to put forth the concept of a card with an
element that is designed to deal 3-5 damage to immortal target for the cost of 5-10 life points (further discussion on this card [idea] is ill-advised for it should be talked about on the forum topic that I, or another user, will create).
EDIT:
I have changed the name of the Upgraded version to make it sound cooler.
