Bell of Lost Souls posted a small set of codex: chaos legions rumours from ghost21. Whilst its very early days in the rumour cycle to say what is true or false, this one caught my eye:
"khornate chrono gladiators"
...What The? Where does "chrono" come in to things? Khornate gladiators, sure. But why are they associated with "time" specifically?
Other highlights for me included "minor chaos powers" being in there and dark mechanicus. But to be honest, all of the rumours presented sound juicy to me! Exciting times.