Alright, so I was dicking around today, I tried to solo Megalobugard as BST/RDM 60. I died.
At any rate, I pulled Megalobugard to where Leshychikhas pop to use as pets. I was swapping them and meleeing with them, Rampaging once in a while. Eventually I got too much hate, to the point where he wouldn't come off me even with Raven gear on. So I used a Hi-Reraiser really quick and died.
That's when Megalobugard despawned. That's odd... I don't recall NMs despawning. Was this a glitch? Its just interesting I think.
And yeah, I reraised and saw he respawned within 30 seconds back in his pop area. No M-Tusk ftl.