Esoobac

Esoobac is a purple colored Lasher boss. It is roaming the ramps at Brimstone Lake Water Refinery. It is rumored that Esoobac has a taste for Telemetry Matrixes, and that it could be the cause as to why the Brimstone Lake Waypoint malfunctions now and then.

You need to kill it as a part of Thunderhead Targets of Opportunity objective "Kill All 9 Thunderhead Named Bosses".

Trivia
It is likely that Esoobac is a tribute to the Red vs. Blue character Caboose. Both characters are approximately the same color purple.