I went in and added Lair of the Orc Shaman as Quest 11 to my Kellar's Keep Quest Book file and decided to edit the Conclusion a bit to flow into it. Quest 10 is Grin's Crag which leads directly into the Conclusion story about the battle in Kellar's Keep and the army's escape through the passage that you've just opened. So the Conclusion needed to remain before the Orc Shaman quest but it needed a little something to flow into that Quest.
I removed the last paragraph and in it's place put this:
However, the day is not yet won. As the army makes their way back through the now-familiar halls of Karak Varn to light and safety, Sir Ragnar takes you aside and tells you of Grawshak, an Orc Shaman who assisted Zargon in the assault, bringing with him soldiers from the Northern Tribes. This sorcerer helped Zargon in his plan and stood by his side through most of the battle, though was noticeably absent in the final wave. His lair is just outside the Great Gate hidden among the hills on the outskirts of the World's Edge Mountains. Sir Ragnar draws you a map and bids you to take some men and go there to defeat Grawshak, delivering a mortal blow to the greenskin army.
This leads directly into the Lair of the Orc Shaman quest. I wanted to add Sir Ragnar to bring him back into the story. In my story, Zargon has instructed him to point the Heroes to Grawshak in the hopes of quietly getting rid of them. Ragnar tells the Heroes about this away from the Emperor and others so he has plausible deniability if they were to meet a horrible end as maybe the Heroes just took it upon themselves to go there.
After that quest I put a slightly reworded version of the last paragraph of the Conclusion to lead into Return of the Witch Lord:
"You have done well, brave Heroes. The Emperor has asked me to express his gratitude. Each of you will receive 500 Gold Crowns for your efforts. But do not let victory deceive you. A dark cloud still hangs over the Empire as the forces of Chaos grow stronger. Do not forget that the Witch Lord lives again. For now, though, rest well my friends. Once I have consulted Loretome, I shall summon you. Together we will find ways to delay Zargon's advance."