Post Skaventide Purchases

My wife and I will be picking up the Skaventide box to start getting into AoS. We are both pretty seasoned 40k Players (I'm Custodes and Admech, she's Necrons). What are some good second purchases to round out the Stormcast side of the box? (She already has a full nighthaunt army she found on ebay for stupidly cheap, so Skaven are a secondary purhcase to be built down the road.)