Reiver Demon — ruling 1

If a creature (such as Clone) enters the battlefield as a copy of this creature, the copy’s “enters-the-battlefield” ability will still trigger as long as you cast that creature spell from your hand.

Reiver Demon : règles, fonctionnement et interactions (MTG)

Reiver Demon 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 When this creature enters, if you cast it from your hand, destroy all nonartifact, nonblack creatures. They can't be regenerated.

How it works : Reiver Demon

Original English text — Wizards of the Coast / Scryfall

#1September 20, 2013· Wizards of the Coast
If a creature (such as Clone) enters the battlefield as a copy of this creature, the copy’s “enters-the-battlefield” ability will still trigger as long as you cast that creature spell from your hand.
No other card is named in this ruling.