Since the Necromantic, Curser and Hexer and anothers indirectly spellcasters craft their spells that traditionally and Mythically recal ill effects in anothers sometimes we could see that the Hermetic Lesser Limit of Arcane Conection is a problem, more since the Leadworker Virtue is exclusive from House Tremere, i think taht there another good way to complete the Cursing Magi.
Tether Magic (Or Tamed Magic) is the piece, with others Sobrenatural, Hermetic and General Virtues, along Story Flaws. Aimla Companion can be a very usefull virtue for a cunning magi, and Ghostly Warder too. Summoning can work better too. Along Binding Magic, is the combination more near to necromancers or Hexer inside Hermetic Tradition. Magical Focus on Summon or Spirits or Necromancy (only Ghost should work well) complete the thing.
Another question: There are a use out of the Hermetic Magic of that Virtue in the warders of Delphii, they can use thir powers by their arms. Could a Ex Myscellanea use the Virtue with others Sobrenatural Virtues and Abilities or only in his Hermetic Magic? Two Virtues, one for those sobrenatural powers?