Ambrose Malachai is the leader of the Ivich Army. He has been around since 2014 or 2015, arriving on the BD Wiki. He is the one who has been behind the war the entire time and showed up very late. It's unknown as to why Ambrose decided to reveal himself, but the reasoning behind that can go in many directions.
He speaks Rhefugi, a demonic language. Overtime he has learned English, but he came speaking Rhefugi. He began to speak English after "being around humans long enough" as he stated in his coming back of August.
Ambrose's real name is Ambrosius, but goes by many other nicknames. Ambrose is known to disappear for large amounts of time as he is more than likely occupied with his outside life. He seems to intervene when it's seriously needed.
There is no pattern in Ambrose appearing and disappearing. He comes and goes as he pleases and can even disappear for almost over a year.
As of February and March of 2016, the way he talked showed as if he was getting a bit more impatient with the way things are going. In August it was confirmed he wants to end the war but there will only be one survivor in it. He is trying to find a way to end the loop, a loop that continuously has brought us back for eons only to fight again and again and again. He isn't sure how to yet, and we hope it stays this way.
It's unknown what happens if Ambrose wins the war for good. We would rather not find out.
As for how you Venkons should deal with him, please read How To: Deal With Ambrose.
STAY AWAY AT ALL COSTS! DO NOT GO TO HIM ALONE.