The Magnus Effect (Good Omens×Shadowhunters)
12 parts Complete Magnus Bane has returned to London after 25 years, looking forward to meeting old friends and the puzzling offer from a Shadowhunter that summoned him to England. Unfortunately, demonic forces have decided to wreak havoc on the exact day, and Magnus is not in the mood for enlisting the Shadow World's help tonight. That leaves only one option- two old, old acquaintances- as old as time itself. Can Magnus set aside his doubts and trust the angel and the demon?
NOTE- this is a short Shadowhunters Universe × Good Omens fanfiction. all characters belong to Cassandra Clare/ Neil Gaiman and Terry Pratchett.