Akos thinks about what he knows about the creatures. There were many spiders in the library, big ones, hairy ones, small ones, venomous, poisonous, jumping, weaving...all kinds. And he researched both them and the giant versions. But even for those, these are big.
Still, spider is a spider and they burn readily. Activating specific runes on his gloves he calls out aloud just in case there are witnesses.
"Titania, grant us your favor and burn these vermin!"
before unleashing stream of leaves laced with burning embers into one of the monsters.