[Svartalfiar]

It is a very venomous spider. The bites probably have an enzyme based poison which makes the small wounds grow large.

He has hundreds of bites from "very venomous" spiders, and he's still walking and talking?

[sport]

I don’t believe that is real spiders that are biting him. I believe it is the spiders that the dope he is shooting up is causing him to see.