Pattern Matcher — ruling 1

You may choose to search your library for nothing and shuffle it, even if you control no other creatures.

Pattern Matcher — ruling 2

If a second Pattern Matcher enters the battlefield under your control, you can have it look at the first Pattern Matcher to search for a third Pattern Matcher.

Pattern Matcher : règles, fonctionnement et interactions (MTG)

Pattern Matcher 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

When this creature enters, you may search your library for a card with the same name as another creature you control, reveal it, put it into your hand, then shuffle.

How it works : Pattern Matcher

Original English text — Wizards of the Coast / Scryfall

#1July 12, 2019· Wizards of the Coast
You may choose to search your library for nothing and shuffle it, even if you control no other creatures.
No other card is named in this ruling.
#2July 12, 2019· Wizards of the Coast
If a second Pattern Matcher enters the battlefield under your control, you can have it look at the first Pattern Matcher to search for a third Pattern Matcher.
No other card is named in this ruling.