Chariots of Tzeentch
From Warhammer - The Old World - Lexicanum
A Chariot of Tzeentch is a chariot available to some of the followers of Tzeentch. One common element to the various forms of this chariot is that it is pulled by flying daemons and the riders are often daemons.
In the Demon Army in the Storm of Chaos they were composed of 2 Flamers on a flying chariot, pulled by two Screamers of Tzeentch. In Daemons of Chaos the chariot was ridden by a herald of Tzeentch.
Gaming reference
During the 5th Edition Chariots of Tzeentch were pulled by Discs of Tzeentch and piloted by one or two pink Horrors.