The year has not been merciful for Horus Heresy. While it started well, with a dedicated rulebook that even I purchased, it did not follow up on that. We have been hit by the plague of Last Chance to Buy, which removed a lot of Legion conversion kits. They killed off the MK II armor line entirely. Eventually, they cut off MK IIIs and MK IVs, which was the only logical moves, as we already have plastics for those. You could still get plenty of those in Betrayal at Calth and Burning of Prospero boxes.