Starfall 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

Starfall deals 3 damage to target creature. If that creature is an enchantment, Starfall deals 3 damage to that creature's controller.

How it works : Starfall

Original English text — Wizards of the Coast / Scryfall

No additional ruling has been published for this card.

Interactions with other cards

These cards' text mentions Starfall.

The Emperor of Palamecia // The Lord Master of Hell

{T}: Add {U} or {R}. Spend this mana only to cast a noncreature spell. Whenever you cast a noncreature spell, if at least four mana was spent to cast it, put a +1/+1 counter on The Emperor of Palamecia. Then if it has three or more +1/+1 counters on it, transform it. Starfall — Whenever The Lord Master of Hell attacks, it deals X damage to each opponent, where X is the number of noncreature, nonland cards in your graveyard.