Oran-Rief, the Vastwood — ruling 1

Oran-Rief's last ability affects all permanents that are green creatures that entered this turn, not just the ones you control.

Oran-Rief, the Vastwood — ruling 2

Oran-Rief's last ability cares about permanents' characteristics at the time the ability resolves, not their characteristics at the time they entered. For example, if a blue creature enters, then is turned green by a spell or ability, then Oran-Rief's second ability resolves, you'll put a +1/+1 counter on that creature.

Oran-Rief, the Vastwood : règles, fonctionnement et interactions (MTG)

Oran-Rief, the Vastwood 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 land enters tapped. : Add . : Put a +1/+1 counter on each green creature that entered this turn.

How it works : Oran-Rief, the Vastwood

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2009· Wizards of the Coast
Oran-Rief's last ability affects all permanents that are green creatures that entered this turn, not just the ones you control.
No other card is named in this ruling.
#2October 1, 2009· Wizards of the Coast
Oran-Rief's last ability cares about permanents' characteristics at the time the ability resolves, not their characteristics at the time they entered. For example, if a blue creature enters, then is turned green by a spell or ability, then Oran-Rief's second ability resolves, you'll put a +1/+1 counter on that creature.
No other card is named in this ruling.