my findings with shroud. ( maybe translation errors, i'm french ). Sign of vampirism, the traits "vampiric" , "vampiric presence" specific to your necromancer works under a shroud.-Sign of vampirism (activated by other necro) when attacking the marked target, and "vampiric presence" of an other necro allow healing under the shroud. Se which does not work / no longer for obscure reasons: zone of darkness + whirl attack combo, leeching bolt activate life siphon damage but not healing under shroud "Soulcleave's Summit" (Rénégat) same observation."Facet of nature" (herald legendary assassin) same observation.=> Small aside, the trait "sign of suffering" (spite) does decrease the cooldown of sign of vampirism, but doesn't change the damage and healing of life siphon. His last ones remain the same outside or under the shroud. : /