Diablo III: Reaper of Souls

I have that thing. I think it's bugged. A lot of the time it'll drop one or even two sentries immediately when I move into a new map. :S

Seems similar to the behavior of the Legendary WD weapon which summons fetishes when you attack, after you move maps you still keep the ones you've summoned. It's weirder since they aren't mobile pets like the WD ones though.