Ok, i have been hunting these in Cape terrigan in area J-8 behind outpost and G-8 right up the first hill, for 3 weeks now 0/60+ so far :( not subing thf as I am bst/whm level 69
For those who wants to camp these here u half to kill spotakers, goblin Alchimists and o yes, they only pop from 20:00 to 4:00. If u time it right, kill goblin at 18:00, doom mage will pop around 20:00 or just after and u can make 2-3 to pop in 1 night in 1 area.
There are other spots they pop here H-8 that i have popped them but area is full of raptor type mobs so very hard to get more then 1 to pop there.
Good luck to all u Mage hunters ^^