Sirius's eyes widen a bit at the mention of an actual giant sea monster. The only thing he has for reference is the giant squid at Hogwarts, but as far as Sirius is aware, he's certainly not tried to destroy any worlds. Couldn't even if he wanted to.

"I've tried," he confesses at Newt's suggestion and his sigh should be every indication of how disappointed in himself he is for his failure. "My magic doesn't seem to work entirely with this sort of condition. The best I've been able to do is heighten his senses here and there, make it so he can taste and touch. Those spells do nothing to control his organs though, really, and they're not long-term.

"I've a mate who knows blood magic, though," he adds, thinking of Kell. "Might there be something in that? I could introduce him to you."