Before the Third War, Kristoff served as a clerk for Grand Marshal Garithos, and served as one of his advisors after the fall of Lordaeron. Kristoff and the other advisors strongly urged Garithos to reconsider his alliance with the Forsaken, believing them to be treacherous. By the time Kristoff was proven right and Garithos met his end at the hands of Varimathras, Kristoff had already left, probably to Theramore.
Kristoff believed that Thrall was the only "civilized" orc and long voiced the fear that if Thrall were dead, the orcs would "revert to form" (they had gained a reputation among humans as mindless savages) and overrun Theramore. When Jaina decided to ally with Thrall against her own father, Daelin, Kristoff decided to take extraordinary action. To that end, he allied himself with the demon Zmodlor in an effort to set off a war between Durotar and Theramore in order to destroy the orcs. However, Zmodlor had also enthralled the orc Burx, one of Thrall's chief warriors, and were setting the orcs and humans against one another. With Jaina absent, he ordered the reinforcement of Northwatch Hold, knowing that the orcs would perceive it as a threatening gesture.
With the aid of Aegwynn, the Guardian of Tirisfal who had banished Zmodlor centuries earlier, Jaina was able to return to Theramore and confronted Kristoff with his crimes. Infuriated by what Kristoff had done, Jaina lashed out with a bolt of lightning intended to exorcise Zmodlor's influence. The effort was successful, but Kristoff died shortly afterwards, his last words an apology for his actions.