When I played my Necro, I found all class uniques by level 70. My druid is level 85 and I’ve yet to see a tempest roar. All I farm is cultist/cannibal dungeons/NM dungeons. I clear 3-4 dungeons, do the legion events then back to the dungeon grind. I’ve gotten at least 3-4 of the other non class uniques already before tempest roar. So yes, it’s super rare.