I really struggled with this mission, but I finally completed it. 1) I directed Ilay directly towards Horncrest, while Isabel gathered resources. 2) After clearing the path to Horncrest and all the heroes joined me, I gave all the Knight army to Friede and sent her to defeat the demons, and I sent Wulvsten and Ilay to the underground castle of the Dark Elves (when Alaric passes through the garrison, don't be alarmed, wait until he passes through the Dwarven garrison, and he won't attack you). 3) After capturing all the Devil castles and the Dungeon castle, I didn't develop them, but accumulated gold and built up Horncrest. 4) I sent Wulvsten to capture the Dwarven garrisons, accumulated the Knight army, and trained the first half of the peasants into Monks, and the second half into Champions. 5) I waited until the last week, gave all the Knight army to Ilay, and sent her to the Dwarven castle. I resurrected the creatures a couple of times and won. 6) For those who don't have Resurrection, you can find it in the Dwarven territory.