IG Deathstar?

50 Guardsmen, Power Axe Sergeants, 5 Lascannons, White Scars Librarius Conclave, 2 regular old Priests and an Inquisitor with the Liber Heresius, Rad Grenades and Psychotroke Grenades. Add Orders and off you go. Alternatively the classic, Azrael and either enough Librarians to roll it or Stern to guarantee Sanctuary. With Priests, congrats, your Guard blob has 3++ rerollables in melee.