Ok here is some relief... I know how to trigger their spawn. I have got 3 hearts now from 7 or so ghasts. Here's what you do... Bind at Gfay zoneline. 1) run on the right wall of zone (facing away from gfay zone) 2) It must be night for this to work 3) track all roaming unded an kill them over an over (helps if you shout for people to kill any roaming they see) 4) Every now and then gate to gfay zone line and go on the right wall facing away from zone line, checking track every couple of seconds for the rhancorous ghasts. There it is. Good luck
-Animas Chordata