Players who storm the tower can unlock a nifty gas mask skin that can be applied to any head armor, as well as a version of the standard underwater breather to wear on dry land. Other rewards include a toxic spore backpack skin and two Toxic Krait miniatures, but you can only access them if you come back...alive.
To top things off, ArenaNet is hosting a Rock the Nightmare music video contest. Break out your best editing skills to create a one-minute video for the song "The Nightmares Within," which can be found on ArenaNet's Soundcloud, and you could win a 3D-printed GW2 guitar or some SteelSeries gaming gear! Nightmares Within will go live on November 12th.