Psychic Surgery — ruling 1

You look at the top two cards of that library as the triggered ability resolves. That happens after your opponent is done shuffling.

Psychic Surgery — ruling 2

If your opponent’s library has one card in it and they are instructed to shuffle that library, Psychic Surgery will trigger. You may’ exile the one card in that library.

Psychic Surgery — ruling 3

In most cases, Green Sun’s Zenith instructs you to shuffle your library twice. Although shuffling that library only once is an acceptable shortcut, Psychic Surgery’s ability will still trigger twice.

Psychic Surgery : règles, fonctionnement et interactions (MTG)

Psychic Surgery is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Whenever an opponent shuffles their library, you may look at the top two cards of that library. You may exile one of those cards. Then put the rest on top of that library in any order.

How it works : Psychic Surgery

Original English text — Wizards of the Coast / Scryfall

#1June 1, 2011· Wizards of the Coast
You look at the top two cards of that library as the triggered ability resolves. That happens after your opponent is done shuffling.
No other card is named in this ruling.
#2June 1, 2011· Wizards of the Coast
If your opponent’s library has one card in it and they are instructed to shuffle that library, Psychic Surgery will trigger. You may’ exile the one card in that library.
No other card is named in this ruling.
#3June 1, 2011· Wizards of the Coast
In most cases, Green Sun’s Zenith instructs you to shuffle your library twice. Although shuffling that library only once is an acceptable shortcut, Psychic Surgery’s ability will still trigger twice.
No other card is named in this ruling.