Gurzigost — ruling 1

You decide how it will assign its damage at the time the ability resolves. This will be prior to actually assigning combat damage.

Gurzigost — ruling 2

If this creature is attacking a planeswalker, assigning its damage as though it weren’t blocked means the damage is assigned to the planeswalker, not to the defending player.

Gurzigost : règles, fonctionnement et interactions (MTG)

Gurzigost 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

At the beginning of your upkeep, sacrifice this creature unless you put two cards from your graveyard on the bottom of your library. , Discard a card: You may have this creature assign its combat damage this turn as though it weren't blocked.

How it works : Gurzigost

Original English text — Wizards of the Coast / Scryfall

#1April 1, 2008· Wizards of the Coast
You decide how it will assign its damage at the time the ability resolves. This will be prior to actually assigning combat damage.
No other card is named in this ruling.
#2April 1, 2008· Wizards of the Coast
If this creature is attacking a planeswalker, assigning its damage as though it weren’t blocked means the damage is assigned to the planeswalker, not to the defending player.
No other card is named in this ruling.