Infernal Sentinel
Infernal Sentinels is the big brother of flamme sentinel and the twin of the frost sentinel. They have the ability to cast rapid short fire beam in series which do small aoe damage on the ground. They also have fast energy shield recovery, good elementals resistances, and high dps.
Infernal sentinel are like frost sentinel, a target of choice for Raise Spectre. They are aggressive, resistant, and always follow you quickly and don't stop shooting at any encounters, even offscreen. They can be enhanced via skills gems like spell echo, fast casting, controlled destruction...
These mobs can be found in and act 3 or 8, in the Solaris temple.