The adoption of TK-like mechanics and a special currency for Horde cap upgrades should be adopted going forward for other hordes. Namely Warriors of Chaos. Getting stronger by fighting is the way to go.
Hordes finally feel like hordes. Being able to block resettlement is also an essential feature to avoid playing whack-a-mole and truly burn down the world Chaos style.
Implementation probably needs some balancing but the general principles are finally there after years of attempts.