BLM's reportedly are gimped ~25% dmg, just like on the regular dragons (and now Ballista... /sigh) This is not counting the resist rate... However, BLM are supposed to be OK on him. The CoP version is very weak to BLM; this one, not so much. He also reportedly has regular dmg -%, so even a plethora of RNG or such would be somewhat ineffective. Perhaps Monks?
The worms are unspecified; however, when you kill them, more respawn. No dice. A strategy I heard was to fight it like KS99 (we need to practice then) with heavy gravity-kiting. Melee build TP on elementals and worms (tricky tricky!) and WS / SC on the Dragon. He has lots of high damage AoE so this is risky... But doable. By the way, nice suggestion, but I don't think we have nearly that number of BLMs xD