Deep-Sea Terror — ruling 1

Deep-Sea Terror’s ability only checks as attackers are declared. After Deep-Sea Terror legally attacks, reducing the number of cards in your graveyard won’t cause it to stop attacking.

Deep-Sea Terror : règles, fonctionnement et interactions (MTG)

Deep-Sea Terror 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

This creature can't attack unless there are seven or more cards in your graveyard.

How it works : Deep-Sea Terror

Original English text — Wizards of the Coast / Scryfall

#1June 22, 2015· Wizards of the Coast
Deep-Sea Terror’s ability only checks as attackers are declared. After Deep-Sea Terror legally attacks, reducing the number of cards in your graveyard won’t cause it to stop attacking.
No other card is named in this ruling.