Overall, the last mission isn't too difficult. Capturing castles with other heroes doesn't present any particular challenges, especially when playing as Illaya. I managed to defeat Chaos several times. But capturing the castle is just insane. I have all high-level creatures (44 of each), including those that appear after defeating the Dark Elves, plus 97 Titans, and my hero is leveled up to 32. But they defeat me incredibly quickly. At the beginning of the battle, almost all of Chaos's creatures open portals, so instead of 165 Cave Lords, there are twice as many, the same goes for Cave Ogres and Demons, and Nightmares. Only the Chaos Archer (Succubus, I think) doesn't summon.