Lowest of the Low - Act 2 Side Quest
Start Location: Beggar's Quarters (outside City of Memphis)
Quest Location: Beggar's Quarters
Objective: Defeat the Shadowstalker enemies
Lowest of the Low can be acquired by speaking with Merab in the Beggar's Quarters (pictured above), a zone just before the City of Memphis. He asks you to clear out all of the Shadowstalker enemies that are in the area just east of where he is. It's a relatively small area and there are only about a dozen Shadowstalker enemies to find here.
As with all quest enemies in this game, the Shadowstalkers' will have their names in purple as well as a faint white aura that surrounds them - shown in my screenshot below. Defeat all of them then return to Merab and speak with him again to complete the quest.