Capítulo 296: Leave Me

"Those are Mycellem Puffs, poisonous fungi that corrupt and mutate living creatures," he explained. 

The spores were inhaled, the living creature will either die from poisoning or mutate into something terrifying. The rat king they had encountered was likely one such victim. As they continued to observe the mushrooms that covered the cave floor, they notices that some of them had been eaten. 

"The Rat King must have eaten the mushrooms as well, which would explain its accelerated mutation," Laina deduced. 

She turned to Titan, realizing he was not protected. Dante seemed to have read her mind. He explained that Titan was immune to the effects of the mushrooms. As a Solar Mastiff, he was immune to all if not most poisons of any form. 

Laina crouched down and gave Titan a pet on his head, "Why aren't you a wonder dog."