Beyond the dark portal Book 11

Two years following the defeat of the Horde and destruction of the Dark Portal from Draenor to Azeroth, a small dimensional rift remains linking the two worlds. 

The orc shaman Ner'Zhul is approached by orc champions resurrected as undead death-knights, with a plan to re-open the Portal and catch the Alliance unaware. 

Using the skull of the traitorous Gul'Dan, the remaining Horde forces distract the Alliance while stealing powerful artifacts to return to Draenor and open new rifts to other worlds. 

The paladin Turalyon joins forces with the elven ranger Alleria, the powerful mage Khadgar, and the dwarven griffon-rider Kurdran to head off the diabolical plans, but their mission is further complicated by the deadly Black Dragonflight's collusion with the Horde.