Quote Originally Posted by jimbosmiff View Post
Can someone fill me in on how this character is useful
Immortal Princess (the black unit, not the platinum Vampire Princess) has a very specific use. When a hard hitting boss arrives, drop Karma on him, activate her skill (1 sec initial due to her being a black), and for ~13 seconds, Karma cannot die, no matter how much the enemy hits her for. She will also give a bit of health to your other units in that time.

Neither of the two Karmas are to be used as Princesses. They are to be used as stallers and gankers, to be dropped and withdrawn.
Properly leveled, they should also hit like a truck.