Harlequins are coming, most likely quicker than expected. The end of this coming weekend's White Dwarf is said to give us the hint, "Dance of Death". Dance of Death is definitely not a reference to Necrons, and it looks like our Harlequin book is just a short couple weeks out.
At This moment we have not seen leaks, so its considered a rumor.
via Archibald_TK on Warseer
End of the Necron WD refers for the following week to "Dance of Death".
So unless the Necrons just discovered an affinity for music...