Vantress Gargoyle — ruling 1

If Vantress Gargoyle attacks a planeswalker, the controller of that planeswalker is the defending player.

Vantress Gargoyle — ruling 2

Vantress Gargoyle's attacking and blocking restrictions are checked only at the moment that you declare it as an attacking or blocking creature. If the defending player loses cards from their graveyard after Vantress Gargoyle attacks, or if you lose cards from your hand after it blocks, it remains in combat.

Vantress Gargoyle : règles, fonctionnement et interactions (MTG)

Vantress Gargoyle 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

Flying This creature can't attack unless defending player has seven or more cards in their graveyard. This creature can't block unless you have four or more cards in hand. : Each player mills a card.

How it works : Vantress Gargoyle

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2019· Wizards of the Coast
If Vantress Gargoyle attacks a planeswalker, the controller of that planeswalker is the defending player.
No other card is named in this ruling.
#2October 4, 2019· Wizards of the Coast
Vantress Gargoyle's attacking and blocking restrictions are checked only at the moment that you declare it as an attacking or blocking creature. If the defending player loses cards from their graveyard after Vantress Gargoyle attacks, or if you lose cards from your hand after it blocks, it remains in combat.
No other card is named in this ruling.