One thing that bothered me with his campaign is that Dark elven beasts quickly become much better than non dark elven ones. This is because DE beasts get a lot of buffs with the red and tech trees, Rakarth and the high beastmasters traits.
As a result after a while the different beasts from other races you struggled to collect become useless. I still try to use the beasts I want in low difficulty but this would never work in legendary difficulty.
Ulthuan, Home of the Asur. If any high elf player is in the hobby too I would suggest you to check this forum.