Arenanet just posted information on the 29 October 2013 patch. Titled “tower of nightmares,” the patch focuses on Kessex Hills, and the new construction the Krait have been slaving away at for a while. The website only mentions the following:
A toxic seed has been sown.
Guarded by magic, fed with evil, it grows.
Rewards for completing the meta-achievement include a Krait obelisk shard, which allows quartz to be charged in the home instances of characters, and allows a new skill point to be earned. The other rewards is a new, universal healing skill titled “antitoxin spray,” which heals a player and cures them of poison, torment, confusion, and a new condition titled toxin.