But yes, that would be a very interesting alternative to something like, oh I dunno, Dark Missionary? Trouble of course being that it can't be used during downtime or when a boss disappears... and would probably be wildly OP in Alliance Raids.
After all, if it wasn't going to affect
everyone who hits the target, just your own group, then why not go the whole 9 yards and just make it a Vampirism group buff? At least then it fits the vague undead theme of DRK (looking at you, LD). And if you combine that
with DMis, you solve the downtime issue.