I’m not saying this is necessarily the route Jagex should take but in OSRS they have the equivalent of the Arraxyte; Nylocas Vasilias. According to their lore they originate from Vampyrium. Jagex has teased us with glimpses of Vampyrium but we’ve never truly been able to visit. I’d like to see a future quest or area accessible via the world gate where we can dive into all their lore. Maybe even a theatre of blood equivalent.