Oramond Factory -1 floor East Raid, he spawns close to right wall and starts walking towards left side, when he touches the wall he dissapears, we've killed him recently with 7 ppl +/- 600 lvl and had few minutes of reserve.
He's walking 1 tile per 10 seconds, and I think he doesn't deal any significant damage, just need fire power to kill it.
I think he's spawning when raid of this section is starting, but not 100% sure if it always happens.