Hes lvl 35, spawn time for all mobs in unrest is 20 mins... I have camped him at least 20 times. I'd say 33% chance that he pops instead of hag ph (on average). Terror is not ph. He drops band everytime unless he drops boots, drops boots like one in 10-15, but Ive seen 2 boots drop consecutively. He pops (or ph) in far right corner if you're looking at it from hallway, far left corner if your standing above pit.
ALWAYS keep your back to the wall when fighting terrors ;)