Rimuru’s fury erupts in That Time I Got Reincarnated as a Slime Light Novel Vol 15 as Veldora’s capture shatters his calm and unleashes his true wrath. Trapped within the Phantom Fortress, Rimuru defies Raphael’s warning, recklessly teleporting into enemy territory to face Velgrynd, the Flame Dragon, and the Imperial army. Witness the rise of the Black Corps... Diablo, Testarossa, Ultima, and Carrera - as they evolve into true Demon Lords, rallying Tempest’s forces for all-out war. This breakdown dives deep into Rimuru’s rage, the Empire’s trap, the Phantom Fortress, and the epic clash that sets the stage for Velgrynd vs Rimuru in Tensura’s most intense battle yet!