The design called for "phosphorescent mushrooms, reminiscent of Zangarmarsh," so our main concern was avoiding making a helm that looked like a giant toadstool sombrero. We’re always looking to incorporate interesting light sources within a raid set, and bioluminescent vegetable growth certainly provides that. Twisting, organic shapes are often key elements of a druid set, and this tier is no exception, with writhing plant roots providing a frame for the glowing clusters of fungi.

Check out the old tiers here: http://us.battle.net/wow/en/blog/3469607