Lithomancer's Focus — ruling 1

Lithomancer’s Focus will prevent damage to the creature from any colorless source that turn, even if that source didn’t exist or wasn’t colorless as Lithomancer’s Focus resolved.

Lithomancer's Focus : règles, fonctionnement et interactions (MTG)

Lithomancer's Focus 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

Target creature gets +2/+2 until end of turn. Prevent all damage that would be dealt to that creature this turn by colorless sources.

How it works : Lithomancer's Focus

Original English text — Wizards of the Coast / Scryfall

#1August 25, 2015· Wizards of the Coast
Lithomancer’s Focus will prevent damage to the creature from any colorless source that turn, even if that source didn’t exist or wasn’t colorless as Lithomancer’s Focus resolved.
No other card is named in this ruling.