Dark Favor — ruling 1

If the creature targeted by Dark Favor is an illegal target when Dark Favor tries to resolve, Dark Favor won't resolve. It won't enter and its "enters" ability won't trigger.

Dark Favor : règles, fonctionnement et interactions (MTG)

Dark Favor 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

Enchant creature When this Aura enters, you lose 1 life. Enchanted creature gets +3/+1.

How it works : Dark Favor

Original English text — Wizards of the Coast / Scryfall

#1September 22, 2011· Wizards of the Coast
If the creature targeted by Dark Favor is an illegal target when Dark Favor tries to resolve, Dark Favor won't resolve. It won't enter and its "enters" ability won't trigger.
No other card is named in this ruling.