Amy casts Notion Rain and chooses to bin Nexus of Fate and keep her other card with the surveil. Does the other card stay on top or is it shuffled in?

Edit: Fixed card tags

Edited Jeff S Higgins (Oct. 9, 2018 04:59:53 PM)

Hi,

The other card stays on top of the library. You're simultaneously shuffling the Nexus into the library and putting the other card on top of your library. Since this is happening at the same time, not one at at time, the card that you choose to keep on top of the library ends up on top of your shuffled library.

This is also confirmed on Magic Rules Manager Eli Shiffrin's Twitter: https://twitter.com/EliShffrn/status/1050041800604303360

Nathan Long
Magic Rules NetRep