The model I'd use is included here, the new Isabella Von Carstein.
Decembra, Queen of the Damned
A countess of the nobility of an Imperial world, her orgies and human sacrifices drove her further and further into the clawed hands of the Chaos Powers. She eventually became as close to the mythical vampires as any of their fallen servants.
War Gear: Love’s Cold Touch – This is the name she’s given to her sword, a dreaded weapon that drains the blood and soul from its victims. This is a power weapon that inflicts Instant Death on any to-wounds roll of 6 no matter their toughness.
The Deepest Eyes: Decembra’s gaze goes beyond enchanting. Her beautiful dark eyes become endless wells that swallow the mind of anyone who gets lost in them anyone looking her way can’t help but notice their sinister shine. She and any unit she joins counts as having both offensive and defensive grenades in close combat. In addition she benefits from the Preferred Enemy rule.
Shadow Walk: Appearing from the darkness itself, Decembra may Infiltrate, Ignores Difficult Terrain, and may pass through Impassable Terrain. She may also start the game in reserve and Deepstrike, bringing any unit she’s attached to with her whether they normally Deepstrike or not.
Bloodlust: She is an Infantry model that counts as a Beast (thus Fleet and charges 12”) and gets +2 Attacks for charging instead of +1.
Immortal: Having absorbed hundreds of souls over the millennia, she is an Eternal Warrior and her save is invulnerable. If Decembra is killed she doesn’t die but is placed back in reserve. She may reenter by outflanking (per Infiltration), deepstriking, or walking on her own board edge.
Queen of the Damned: So alluring are her wicked charms that souls not strong enough to resist are forced to follow her for eternity. Infantry, Jump Infantry, Bikers, and Jetbikers who are personally killed by her make a Ld check upon their death. Any killed as a result of a Sweeping Advance do so at -2 Ld, so fierce is her wrath. Those that fail return to life as her slaves immediately following the combat phase—those that are Infantry immediately join her unit. These models are exactly as they were in life and are now Fearless and subject to Rage unless joined by her. Models of different types must form units together. If Decembra is killed all current undead slaves are instantly removed from the board.