Many have pointed out that Death aura is not enough to use the new pact form and I agree.
At the same time, I think that a very good solution to pump negative healing in a comparable, but different way than mage does is to add vampirism to the negative dmg portion of the pact. Devs can adjust how much 10%, 20%.. full healing... They could even remove death aura for necrotic blast and this "drain" from aura, to completely lock warlock in an offensive or no healing reward.
I think this change satisfy my wish for a true "drain life" spells stereotype that DDO lacks, that synergize with Soul Eater very well thematically, draining life from enemies along with Steal Life Force enhancement (that ALREADY heals if u are undead!). But I think this enhancement could be better if it was a dot drain spell with comparable healing to lesser death or death aura.
People could even overlook the fact that u cant dmg ou heal from the undead, so exciting this change can be.