Triggered bosses?????

K so I was running around in Varajar Fells working on my Norn title since this place has sweet points of 4000+ by clearing the place and I noticed yesterday that when I cleared so many mobs that a boss would appear. I decided today I would work my way around the other way to see what hapens and it happened again. I am not sure when it triggers this boss to appear but shown in the first screenshot trigger1 you will see 4 imps and a frozen elemental in that area in back to the left. Now I killed those and then went around and cleared the rest of the map and came back here after and now there is 4 imps and a boss named Dazehl Brainfreezer.

Anyways no idea if anyone has posted about this but thought it was interesting that there is triggered bosses now after so many points or maybe it has to do with hunter level. No idea.

Anyone know how this is triggered?

i think they spawn when you kill the ice imps around that spot, they just did for me...

but i did kill over 300 enemies before killing those imps..

kill all the imps around the lake and he spawns, i thought about clearing the map and looking for spawned bosses but i dont have time