[Redeyes]

By the same logic, shouldn't blackheart work offensively when sieging castles?
Try it with Bane Lords for a thug-chassis.
They are reasonably cheap, have great base stats and (most importantly) are unaffected by the encumbrance from the chest wound.

Though I imagine a Black Servant would be great as well.
Truth be told, I haven't tried the heart with undead so I don't know if it will work. Heading out to do it now.

Edit: tried it on a Vampire Count of Ulm and a Black Servant and it worked with both