Ba'al is a demon overlord in the Black Ring and one of the Damned One's mightiest minions. It was he who lead the Invasion of Valley of Shrines that lead to Lord Lovis' downfall and the valley's renaming to Broken Valley.
In Divinity II: Ego Draconis Ba'al is sent in search of the Hall of Echoes Sigil at the Broken Valley Mine, and is met by the Slayer. He can be mindread to gain two skill points before being defeated and acquiring the Sigil.
Ba'al is met once again inside the Hall of Echoes. He can be mindread a second time to gain an additional skill point before being defeated.