Shouldn’t the first one show up in Soulforge during any Hellcrag week? I know I have it, but I don’t recall exactly where from (and I’m not seeing it in this week’s crafting list either).
… okay, so Ruby-Biter debuted with the Hellcrag Kingdom Pass as the Lv.50 free reward. According to the same post:
The second one is linked to an Immortal Troop, so you would need to play PVP, earn Burning Marks (from PVP season achievements) and acquire/upgrade the stated Immortal to Lv.7 (which is a lot).