Irenicus is an extremely powerful mage and the primary villain in
Baldur's Gate II:
Shadows of Amn.
The plot of the
game revolves around the heritage of the primary protagonist, you. You are the offspring of an evil God,
Bhaal. This gives you some interesting and cool powers that develop over the course of the game.
Irenicus, however, wishes to utilize your powers for his own purpose. Without giving too much away concerning BGII, basically this baddy wants to steal your soul and use it for himself.
There are times during the game when Irenicus is a real bitch, casting
Protection from Normal Weapons, Protection from
Magic Weapons,
Greater Globe of Invulnerability, and then throwing out
Time Stops and
Banshee Wails. In one of the first battles with him, I've had all my characters simultaneously die or run away in confusion/fear. Very annoying.