Need advice for a birthday gift for a Nurgle player

A friend of mine and me just dived into AoS; he took Maggotkin of Nurgle while I got Khorne.

So far we have just started assembling and painting stuff and haven't played the game yet (at all, not only these two armies).

I'd like to pick up something for his birthday but am unsure what to take.

So far he got the Battletome and the Warscroll cards, the Nurgle Start Collecting box, the Glottkins and the Lord of Blights.

I'm basically torn between the Blightkings and a box of the new Malign Sorcery.

The Blightkings seem to fit perfectly into his list (I guess at least) while the sorcery adds some nice 2nd edition flair to our upcomming games. However I'm not sure if nurgle would be using them at all.

Would be cool getting some feedback, thanks in advance! :)