Kidd's Black Armor aka: Kill Lord Cerebus

From AEWiki

You must first kill 200 Dark Guardians (To do this you must purchase Broken Finger Dungeon access via the game store) and then speak to Bobby Kidd. You will find him moping around the Broken Finger bank area. He will ask you to avenge the death of his father by slaying the demonic dog, Lord Cerebus.

Cerebus is a giant canine found on the 2nd level of Broken Finger Dungeon. You'll need a strong party to take him down. Return to Bobby Kidd for your reward when you receive the message that you have slain the beast for Bobby Kidd.

You will receive 300,000 e-pool and Bobby will give you his dad's old armor: Kidd's Black Armor.