I love blood Pangaea.
Yes the slaves appear as little people in your gem stack. But in combat they come out and be ladies in white robes which means they can be killed.
The Pandemoniac can find sites. Especially search anywhere that has rotten unrest you cant explain. He can make interesting blood items if you research construction.
My favorite tactic is to make the heart that turns him into an assassin. Then give him slaves, position him way up to the front, and tell him to cast "Hellbind Heart" during attacks.
If he converts the enemy commander then you will get a combat also where the commander attacks his own troops. Keep doing assasinations until the Last commander and watch the troops rout for being leaderless.
