Random boss spawn on corrupt irradiated t15 map?

Just wondering what I just killed , I was clearing a t15 corrupt, irradiated map and a boss spawned in looked like it had legs like azmodan dark fiery 4 legs , but it died so fast I couldn't get a proper look at it .

Can anyone tell me what it was ? I'm confused what it was but can't find any info

Edit :also make console text size bigger because I couldn't even read its name on the boss bar

That's the unique beyond mob that spawns if you kill enough mobs in one place. He dies fast and drops no loot as far as I can tell from the handful of kills I got.

That's the legacy of one of POEs best leagues.

Good ol' K'Tash the Hate Shepherdtersta



In poe1 you could get a version of them as a spectre. was massive and made so much noise XD