Keeper of the Lens — ruling 1

Keeper of the Lens allows you to look at face-down creatures you don’t control whenever you want to, even if you don’t have priority. This action doesn’t use the stack.

Keeper of the Lens — ruling 2

Keeper of the Lens doesn’t stop your opponents from looking at face-down creatures they control.

Keeper of the Lens — ruling 3

Keeper of the Lens doesn’t let you look at other players’ face-down spells while they’re on the stack.

Keeper of the Lens : règles, fonctionnement et interactions (MTG)

Keeper of the Lens 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

You may look at face-down creatures you don't control any time.

How it works : Keeper of the Lens

Original English text — Wizards of the Coast / Scryfall

#1February 25, 2015· Wizards of the Coast
Keeper of the Lens allows you to look at face-down creatures you don’t control whenever you want to, even if you don’t have priority. This action doesn’t use the stack.
No other card is named in this ruling.
#2February 25, 2015· Wizards of the Coast
Keeper of the Lens doesn’t stop your opponents from looking at face-down creatures they control.
No other card is named in this ruling.
#3February 25, 2015· Wizards of the Coast
Keeper of the Lens doesn’t let you look at other players’ face-down spells while they’re on the stack.
No other card is named in this ruling.