Duskmantle

Duskmantle was the guildhall of House Dimir on Ravnica during Szadek's reign. It was located in the Undercity. After Szadek's demise, both the location and way of gaining entry was lost. Lazav recreated the structure in a different part of the Undercity, shielding it with potent memory wards (not unlike those of the original guildhall).