Although technically an 'Empyre' tie-in, August 26's X-Men #11 (opens in new tab) looks to be unofficially a prelude to this fall's 'X of Swords' crossover event.
This issue is written by Marvel's 'Head of X' Jonathan Hickman, along with series artist Leinil Francis Yu. Check out this preview:
Marvel's description for this issue is a bit vague, saying simply "The trees are killing the children!" Our guess is "the trees" would be plant-like villains of Empyre, the Cotati - but could also refer to the trees on the island of Arakko, especially given the trees (and tree stump) in the above preview.
As readers of the current 'Dawn of X' era know, mutantkind has built a home on the living island Krakoa, even incorporating even mutants who were once the worst enemies of the X-Men into their society – including Apocalypse. Like Krakoa, Arakko is a living island (notice that their names are anagrams for each other) where Apocalypse once ruled, and where he maintains a cabal of warriors working on his secret machinations – the Swordbearers of Arakko.
There are ten members of that group: Pogg Ur-Pogg, The White Sword, Solem, Isca the Unbeaten, Bei the Blood Moon, Redroot the Forest, Summoner, War, Death, and a still-classified Swordbearer.
While the identity of that mysterious member has been kept secret, we've gone through the clues to speculate that it could be classic X-Men member Storm (opens in new tab).
The answer to that, and more, appears to begin to be answered in this issue of X-Men which goes on sale August 26.