Uchbenbak, the Great Mistake — ruling 1

Cards with the ability word "descend N" have abilities that care if you have at least N permanent cards in your graveyard.

Uchbenbak, the Great Mistake — ruling 2

Some descend triggered abilities include intervening "if" clauses (i.e. "if you have [four or eight] permanent cards in your graveyard" in the middle of the ability). Each of these abilities checks your graveyard at the moment it would trigger to see if it does. If you don't have the required number of permanent cards in your graveyard at that time, the ability doesn't trigger at all. If it does trigger, it will check again as it tries to resolve. If you don't have the required number of permanent cards in your graveyard at that time, the ability won't resolve and none of its effects will happen.

Uchbenbak, the Great Mistake — ruling 3

Finality counters work on any permanent, not only creatures. If a permanent with a finality counter on it would be put into a graveyard from the battlefield, exile it instead.

Uchbenbak, the Great Mistake — ruling 4

Finality counters don't stop permanents from going to zones other than the graveyard from the battlefield. For example, if a permanent with a finality counter on it would be put into its owner's hand from the battlefield, it does so normally.

Uchbenbak, the Great Mistake — ruling 5

Finality counters aren't keyword counters, and a finality counter doesn't give any abilities to the permanent it's on. If that permanent loses its abilities and then would go to a graveyard, it will still be exiled instead.

Uchbenbak, the Great Mistake — ruling 6

Multiple finality counters on a single permanent are redundant.

Uchbenbak, the Great Mistake : règles, fonctionnement et interactions (MTG)

Uchbenbak, the Great Mistake 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

Vigilance, menace Descend 8 — : Return this card from your graveyard to the battlefield with a finality counter on it. Activate only if there are eight or more permanent cards in your graveyard and only as a sorcery. (If a creature with a finality counter on it would die, exile it instead.)

How it works : Uchbenbak, the Great Mistake

Original English text — Wizards of the Coast / Scryfall

#1November 10, 2023· Wizards of the Coast
Cards with the ability word "descend N" have abilities that care if you have at least N permanent cards in your graveyard.
No other card is named in this ruling.
#2November 10, 2023· Wizards of the Coast
Some descend triggered abilities include intervening "if" clauses (i.e. "if you have [four or eight] permanent cards in your graveyard" in the middle of the ability). Each of these abilities checks your graveyard at the moment it would trigger to see if it does. If you don't have the required number of permanent cards in your graveyard at that time, the ability doesn't trigger at all. If it does trigger, it will check again as it tries to resolve. If you don't have the required number of permanent cards in your graveyard at that time, the ability won't resolve and none of its effects will happen.
No other card is named in this ruling.
#3November 10, 2023· Wizards of the Coast
Finality counters work on any permanent, not only creatures. If a permanent with a finality counter on it would be put into a graveyard from the battlefield, exile it instead.
No other card is named in this ruling.
#4November 10, 2023· Wizards of the Coast
Finality counters don't stop permanents from going to zones other than the graveyard from the battlefield. For example, if a permanent with a finality counter on it would be put into its owner's hand from the battlefield, it does so normally.
No other card is named in this ruling.
#5November 10, 2023· Wizards of the Coast
Finality counters aren't keyword counters, and a finality counter doesn't give any abilities to the permanent it's on. If that permanent loses its abilities and then would go to a graveyard, it will still be exiled instead.
No other card is named in this ruling.
#6November 10, 2023· Wizards of the Coast
Multiple finality counters on a single permanent are redundant.
No other card is named in this ruling.