[Citation required]
The original followers led by Magister Umbric were enough to be considered a threat to all of Quel'Thalas.
The Ren'dorei as a faction include Blood and High elf scholars as well as, potentially, the Allerian Expedition led by Auric Sunchaser. Now that Alleria Windrunner has returned from Argus, the Alleria Expedition might have rejoined the fold.