Druids of the Flame

The Druids of the Flame are a sect of druids loyal to Ragnaros the Firelord, led by his new majordomo Fandral Staghelm. These vile creatures have turned their backs on Cenarius' teachings and now worship the Fire Lord, Ragnaros. Twisted by his insane power, they desire nothing more than to bury everything in ash. They operate mainly in the Firelands.

During the quest quest:The Nordrassil Summit, Thrall explicitly refers to them as members of the Twilight's Hammer.

Abilities
The Druids of the Flame appear to have gained new shapeshift abilities: Flame Cat Form, Flame Scorpion Form, fire crow and a firehawk. They can also cast a flaming Entangling Roots, which not only roots the target but also burns them in flames, and teleport using a firey version of Moonfire. They often appear as meteors falling from the sky.

Speculation
Since Leyara was inducted into the organization due to being highly disillusioned with Malfurion's passive stance in regards to the Horde, it is possible that other members of the Druids of the Flame joined for similar reasons. It is also possible that they are holdout loyalists of Fandral Staghelm, after the events of Stormrage.