Fiend of the Shadows — ruling 1

Playing a card exiled with Fiend of the Shadows follows all the normal rules for playing that card. You must pay its costs, and you must follow all timing restrictions, for example.

Fiend of the Shadows — ruling 2

You may only play the card, meaning play it as a land or cast it as a spell. It's not in your hand. You can't discard it, activate its cycling abilities, and so on.

Fiend of the Shadows — ruling 3

As long as the card remains exiled, you may still play it, even if Fiend of the Shadows leaves the battlefield or changes controllers.

Fiend of the Shadows — ruling 4

If this creature deals combat damage to multiple players simultaneously, perhaps because some combat damage was redirected, its ability will trigger for each of those players.

Fiend of the Shadows : règles, fonctionnement et interactions (MTG)

Fiend of the Shadows 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 Whenever this creature deals combat damage to a player, that player exiles a card from their hand. You may play that card for as long as it remains exiled. Sacrifice a Human: Regenerate this creature.

How it works : Fiend of the Shadows

Original English text — Wizards of the Coast / Scryfall

#1January 22, 2011· Wizards of the Coast
Playing a card exiled with Fiend of the Shadows follows all the normal rules for playing that card. You must pay its costs, and you must follow all timing restrictions, for example.
No other card is named in this ruling.
#2January 22, 2011· Wizards of the Coast
You may only play the card, meaning play it as a land or cast it as a spell. It's not in your hand. You can't discard it, activate its cycling abilities, and so on.
No other card is named in this ruling.
#3January 22, 2011· Wizards of the Coast
As long as the card remains exiled, you may still play it, even if Fiend of the Shadows leaves the battlefield or changes controllers.
No other card is named in this ruling.
#4January 22, 2011· Wizards of the Coast
If this creature deals combat damage to multiple players simultaneously, perhaps because some combat damage was redirected, its ability will trigger for each of those players.
No other card is named in this ruling.