The search ability lets you find cards whose mana values are each equal to exactly 9, such as other Grozoths.

Grozoth : règles, fonctionnement et interactions (MTG)

Grozoth 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

Defender (This creature can't attack.) When this creature enters, you may search your library for any number of cards that have mana value 9, reveal them, put them into your hand, then shuffle. : This creature loses defender until end of turn. Transmute (, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

How it works : Grozoth

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2005· Wizards of the Coast
The search ability lets you find cards whose mana values are each equal to exactly 9, such as other Grozoths.
No other card is named in this ruling.