Over on Facebook images of what appears to be an Age of Sigmar Warhammer Heroes series of figures have surfaced.

Each of the models can be used as Primes for your Stormcast Eternals units, aside from the Knight Arcanum who appears to be the rarest mini in the set. The original poster thinks these will arrive in December.

I have no other source other than a Facebook post, however these seem legit to me. We’ll likely see an announcement on Warhammer Community soon.