Haunting Apparition — ruling 1

You choose one opposing player when it enters and it only affects that one player. This choice is not changed even if this card changes controllers. This card becomes useless but stays on the battlefield if the chosen player leaves the game.

Haunting Apparition : règles, fonctionnement et interactions (MTG)

Haunting Apparition 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 As this creature enters, choose an opponent. Haunting Apparition's power is equal to 1 plus the number of green creature cards in the chosen player's graveyard.

How it works : Haunting Apparition

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
You choose one opposing player when it enters and it only affects that one player. This choice is not changed even if this card changes controllers. This card becomes useless but stays on the battlefield if the chosen player leaves the game.
No other card is named in this ruling.