Malign Portents gives Wizards a spell called Pall of Doom which effects the bravery of an enemy unit. It also offers two new command abilities:
Malign Portents introduces Prophecy Points which work similarly to CP in Warhammer 40,000. Skills or tactics can be played by expending PPs, which are generated a number of ways for example - fielding one of the 4 new characters.
All in all its a pretty good book. It's not my style of gameplay (introduces too many random or 'free' skills but I imagine it could be quite popular.