Well, Syrlya does live in a lot of blood. But he's pretty sure he's an outlier, and that is not how average civilians live. He lets Foster rave without interruption, but his expression becomes slowly blanker and less connected as it goes on. Briefly, he regrets asking.

"Right," there's no point pedantically arguing 'everything is blood' (he's pretty sure rocks don't have blood) so he's just going to brush right past that. Foster's just very passionate about his weird hobbies, sure, he can roll with that. "But what does your blood magic do?"

The spells, Foster. He's asking about the spells.