I just found 5 Ichthian Stingers from the same pack on XMAX while farming for Icescale Gear. 
This run was crazy, total yield from one clear: 6 Stingers, 2 Shells, Icescale Helm, Bracers, Chest, and Legs plus a Whomper.

Hi lightdevourer82

The achievement "Hardcore Player" and the achievements for finishing legendary difficulty with the different classes pops between the second to last and last phase of the endboss for Ragnarok. For me it poped during the transition without even having killed the boss.

Hope this helps. Greetings